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Fuel economy in automobiles

January 01, 1970

The fuel economy of an automobile relates to the distance traveled by a vehicle and the amount of fuel consumed. Consumption can be expressed in terms of the volume of fuel to travel a distance, or the distance traveled per unit volume of fuel consumed. Since fuel consumption of vehicles is a significant factor in air pollution, and since the importation of motor fuel can be a large part of a nation's foreign trade, many countries impose requirements for fuel economy.

Fuel consumption monitor from a 2006 Honda Airwave. The displayed fuel economy is 18.1 km/L (5.5 L/100 km; 43 mpg‑US).
A Briggs and Stratton Flyer from 1916. Originally an experiment in creating a fuel-saving automobile in the United States, the vehicle weighed only 135 lb (61.2 kg) and was an adaptation of a small gasoline engine originally designed to power a bicycle.[1]

Different methods are used to approximate the actual performance of the vehicle. The energy in fuel is required to overcome various losses (wind resistance, tire drag, and others) encountered while propelling the vehicle, and in providing power to vehicle systems such as ignition or air conditioning. Various strategies can be employed to reduce losses at each of the conversions between the chemical energy in the fuel and the kinetic energy of the vehicle. Driver behavior can affect fuel economy; maneuvers such as sudden acceleration and heavy braking waste energy.

Electric cars do not directly burn fuel, and so do not have fuel economy per se, but equivalence measures, such as miles per gallon gasoline equivalent have been created to attempt to compare them.

Quantities and units of measure edit

 
Conversion from mpg to L/100 km: blue, U.S. gallon; red, imperial gallon

The fuel efficiency of motor vehicles can be expressed in multiple ways:

  • Fuel consumption is the amount of fuel used per unit distance; for example, litres per 100 kilometres (L/100 km). The lower the value, the more economic a vehicle is (the less fuel it needs to travel a certain distance); this is the measure generally used across Europe (except the UK, Denmark and The Netherlands - see below), New Zealand, Australia and Canada. Also in Uruguay, Paraguay, Guatemala, Colombia, China, and Madagascar.[citation needed], as also in post-Soviet space.
  • Fuel economy is the distance travelled per unit volume of fuel used; for example, kilometres per litre (km/L) or miles per gallon (MPG), where 1 MPG (imperial) ≈ 0.354006 km/L. The higher the value, the more economic a vehicle is (the more distance it can travel with a certain volume of fuel). This measure is popular in the US and the UK (mpg), but in Europe, India, Japan, South Korea and Latin America the metric unit km/L is used instead.

The formula for converting to miles per US gallon (3.7854 L) from L/100 km is  , where   is value of L/100 km. For miles per Imperial gallon (4.5461 L) the formula is  .

In parts of Europe, the two standard measuring cycles for "litre/100 km" value are "urban" traffic with speeds up to 50 km/h from a cold start, and then "extra urban" travel at various speeds up to 120 km/h which follows the urban test. A combined figure is also quoted showing the total fuel consumed in divided by the total distance traveled in both tests.

Fuel economy can be expressed in two ways:

Units of fuel per fixed distance
Generally expressed in liters per 100 kilometers (L/100 km), used in most European countries, China, South Africa, Australia and New Zealand. Irish law allows for the use of miles per imperial gallon, alongside liters per 100 kilometers.[2] Canadian law requires fuel economy to be measured in both liters per 100 kilometers and miles per imperial gallon.[3][4][5] Liters per 100 kilometers may be used alongside miles per imperial gallon in the UK. The window sticker on new US cars displays the vehicle's fuel consumption in US gallons per 100 miles, in addition to the traditional mpg number.[6] A lower number means more efficient, while a higher number means less efficient.
Units of distance per fixed fuel unit
Miles per gallon (mpg) are commonly used in the United States, the United Kingdom, and Canada (alongside L/100 km). Kilometers per liter (km/L) are more commonly used elsewhere in the Americas, Asia, parts of Africa and Oceania. In the Levant km/20 L is used, known as kilometers per tanaka, a metal container which has a volume of twenty liters. When mpg is used, it is necessary to identify the type of gallon: the imperial gallon is 4.54609 liters, and the U.S. gallon is 3.785 liters. When using a measure expressed as distance per fuel unit, a higher number means more efficient, while a lower number means less efficient.

Conversions of units:

Miles per US gallon → L/100 km:       L/100 km → Miles per US gallon:  
Miles per Imperial gallon → L/100 km:       L/100 km → Miles per Imperial gallon:  
         
Miles per US gallon → km/20 L:  
L/100 km → km/20 L:  
         
Miles per US gallon → Miles per Imperial gallon:  
Miles per Imperial gallon → Miles per US gallon:  

Statistics edit

 
Trucks' share of US vehicles produced, has tripled since 1975. Though vehicle fuel efficiency has increased within each category, the overall trend toward less efficient types of vehicles has offset some of the benefits of greater fuel economy and reduction of carbon dioxide emissions.[7] Without the shift towards SUVs, energy use per unit distance could have fallen 30% more than it did from 2010 to 2022.[8]

While the thermal efficiency (mechanical output to chemical energy in fuel) of petroleum engines has increased since the beginning of the automotive era, this is not the only factor in fuel economy. The design of automobile as a whole and usage pattern affects the fuel economy. Published fuel economy is subject to variation between jurisdiction due to variations in testing protocols.

One of the first studies to determine fuel economy in the United States was the Mobil Economy Run, which was an event that took place every year from 1936 (except during World War II) to 1968. It was designed to provide real, efficient fuel efficiency numbers during a coast-to-coast test on real roads and with regular traffic and weather conditions. The Mobil Oil Corporation sponsored it and the United States Auto Club (USAC) sanctioned and operated the run. In more recent studies, the average fuel economy for new passenger car in the United States improved from 17 mpg (13.8 L/100 km) in 1978 to more than 22 mpg (10.7 L/100 km) in 1982.[9] The average[a] fuel economy for new 2020 model year cars, light trucks and SUVs in the United States was 25.4 miles per US gallon (9.3 L/100 km).[10] 2019 model year cars (ex. EVs) classified as "midsize" by the US EPA ranged from 12 to 56 mpgUS (20 to 4.2 L/100 km)[11] However, due to environmental concerns caused by CO2 emissions, new EU regulations are being introduced to reduce the average emissions of cars sold beginning in 2012, to 130 g/km of CO2, equivalent to 4.5 L/100 km (52 mpgUS, 63 mpgimp) for a diesel-fueled car, and 5.0 L/100 km (47 mpgUS, 56 mpgimp) for a gasoline (petrol)-fueled car.[12]

The average consumption across the fleet is not immediately affected by the new vehicle fuel economy: for example, Australia's car fleet average in 2004 was 11.5 L/100 km (20.5 mpgUS),[13] compared with the average new car consumption in the same year of 9.3 L/100 km (25.3 mpgUS)[14]

Speed and fuel economy studies edit

 
1997 fuel economy statistics for various US models

Fuel economy at steady speeds with selected vehicles was studied in 2010. The most recent study[15] indicates greater fuel efficiency at higher speeds than earlier studies; for example, some vehicles achieve better fuel economy at 100 km/h (62 mph) rather than at 70 km/h (43 mph),[15] although not their best economy, such as the 1994 Oldsmobile Cutlass Ciera with the LN2 2.2L engine, which has its best economy at 90 km/h (56 mph) (8.1 L/100 km (29 mpg‑US)), and gets better economy at 105 km/h (65 mph) than at 72 km/h (45 mph) (9.4 L/100 km (25 mpg‑US) vs 22 mpg‑US (11 L/100 km)). The proportion of driving on high speed roadways varies from 4% in Ireland to 41% in the Netherlands.

When the US National Maximum Speed Law's 55 mph (89 km/h) speed limit was mandated from 1974 to 1995, there were complaints that fuel economy could decrease instead of increase. The 1997 Toyota Celica got better fuel-efficiency at 105 km/h (65 mph) than it did at 65 km/h (40 mph) (5.41 L/100 km (43.5 mpg‑US) vs 5.53 L/100 km (42.5 mpg‑US)), although even better at 60 mph (97 km/h) than at 65 mph (105 km/h) (48.4 mpg‑US (4.86 L/100 km) vs 43.5 mpg‑US (5.41 L/100 km)), and its best economy (52.6 mpg‑US (4.47 L/100 km)) at only 25 mph (40 km/h). Other vehicles tested had from 1.4 to 20.2% better fuel-efficiency at 90 km/h (56 mph) vs. 105 km/h (65 mph). Their best economy was reached at speeds of 40 to 90 km/h (25 to 56 mph) (see graph).[15]

Officials hoped that the 55 mph (89 km/h) limit, combined with a ban on ornamental lighting, no gasoline sales on Sunday, and a 15% cut in gasoline production, would reduce total gasoline consumption by 200,000 barrels a day, representing a 2.2% drop from annualized 1973 gasoline consumption levels.[16][b] This was partly based on a belief that cars achieve maximum efficiency between 40 and 50 mph (65 and 80 km/h) and that trucks and buses were most efficient at 55 mph (89 km/h).[18]

In 1998, the U.S. Transportation Research Board footnoted an estimate that the 1974 National Maximum Speed Limit (NMSL) reduced fuel consumption by 0.2 to 1.0 percent.[19] Rural interstates, the roads most visibly affected by the NMSL, accounted for 9.5% of the U.S' vehicle-miles-traveled in 1973,[20] but such free-flowing roads typically provide more fuel-efficient travel than conventional roads.[21] [22] [23]

Discussion of statistics edit

A reasonably modern European supermini and many mid-size cars, including station wagons, may manage motorway travel at 5 L/100 km (47 mpg US/56 mpg imp) or 6.5 L/100 km in city traffic (36 mpg US/43 mpg imp), with carbon dioxide emissions of around 140 g/km.

An average North American mid-size car travels 21 mpg (US) (11 L/100 km) city, 27 mpg (US) (9 L/100 km) highway; a full-size SUV usually travels 13 mpg (US) (18 L/100 km) city and 16 mpg (US) (15 L/100 km) highway. Pickup trucks vary considerably; whereas a 4 cylinder-engined light pickup can achieve 28 mpg (8 L/100 km), a V8 full-size pickup with extended cabin only travels 13 mpg (US) (18 L/100 km) city and 15 mpg (US) (15 L/100 km) highway.

The average fuel economy for all vehicles on the road is higher in Europe than the United States because the higher cost of fuel changes consumer behaviour. In the UK, a gallon of gas without tax would cost US$1.97, but with taxes cost US$6.06 in 2005. The average cost in the United States was US$2.61.[24]

European-built cars are generally more fuel-efficient than US vehicles. While Europe has many higher efficiency diesel cars, European gasoline vehicles are on average also more efficient than gasoline-powered vehicles in the USA. Most European vehicles cited in the CSI study run on diesel engines, which tend to achieve greater fuel efficiency than gas engines. Selling those cars in the United States is difficult because of emission standards, notes Walter McManus, a fuel economy expert at the University of Michigan Transportation Research Institute. "For the most part, European diesels don’t meet U.S. emission standards", McManus said in 2007. Another reason why many European models are not marketed in the United States is that labor unions object to having the big 3 import any new foreign built models regardless of fuel economy while laying off workers at home.[25]

An example of European cars' capabilities of fuel economy is the microcar Smart Fortwo cdi, which can achieve up to 3.4 L/100 km (69.2 mpg US) using a turbocharged three-cylinder 41 bhp (30 kW) Diesel engine. The Fortwo is produced by Daimler AG and is only sold by one company in the United States. Furthermore, the world record in fuel economy of production cars is held by the Volkswagen Group, with special production models (labeled "3L") of the Volkswagen Lupo and the Audi A2, consuming as little as 3 L/100 km (94 mpg‑imp; 78 mpg‑US).[26][clarification needed]

Diesel engines generally achieve greater fuel efficiency than petrol (gasoline) engines. Passenger car diesel engines have energy efficiency of up to 41% but more typically 30%, and petrol engines of up to 37.3%, but more typically 20%. A common margin is 25% more miles per gallon for an efficient turbodiesel.

For example, the current model Skoda Octavia, using Volkswagen engines, has a combined European fuel efficiency of 41.3 mpg‑US (5.70 L/100 km) for the 105 bhp (78 kW) petrol engine and 52.3 mpg‑US (4.50 L/100 km) for the 105 bhp (78 kW) — and heavier — diesel engine. The higher compression ratio is helpful in raising the energy efficiency, but diesel fuel also contains approximately 10% more energy per unit volume than gasoline which contributes to the reduced fuel consumption for a given power output.

In 2002, the United States had 85,174,776 trucks, and averaged 13.5 miles per US gallon (17.4 L/100 km; 16.2 mpg‑imp). Large trucks, over 33,000 pounds (15,000 kg), averaged 5.7 miles per US gallon (41 L/100 km; 6.8 mpg‑imp).[27]

Truck fuel economy
GVWR lbs Number Percentage Average miles per truck fuel economy Percentage of fuel use
6,000 lbs and less 51,941,389 61.00% 11,882 17.6 42.70%
6,001 – 10,000 lbs 28,041,234 32.90% 12,684 14.3 30.50%
Light truck subtotal 79,982,623 93.90% 12,163 16.2 73.20%
10,001 – 14,000 lbs 691,342 0.80% 14,094 10.5 1.10%
14,001 – 16,000 lbs 290,980 0.30% 15,441 8.5 0.50%
16,001 – 19,500 lbs 166,472 0.20% 11,645 7.9 0.30%
19,501 – 26,000 lbs 1,709,574 2.00% 12,671 7 3.20%
Medium truck subtotal 2,858,368 3.40% 13,237 8 5.20%
26,001 – 33,000 lbs 179,790 0.20% 30,708 6.4 0.90%
33,001 lbs and up 2,153,996 2.50% 45,739 5.7 20.70%
Heavy truck subtotal 2,333,786 2.70% 44,581 5.8 21.60%
Total 85,174,776 100.00% 13,088 13.5 100.00%

The average economy of automobiles in the United States in 2002 was 22.0 miles per US gallon (10.7 L/100 km; 26.4 mpg‑imp). By 2010 this had increased to 23.0 miles per US gallon (10.2 L/100 km; 27.6 mpg‑imp). Average fuel economy in the United States gradually declined until 1973, when it reached a low of 13.4 miles per US gallon (17.6 L/100 km; 16.1 mpg‑imp) and gradually has increased since, as a result of higher fuel cost.[28] A study indicates that a 10% increase in gas prices will eventually produce a 2.04% increase in fuel economy.[29] One method by car makers to increase fuel efficiency is lightweighting in which lighter-weight materials are substituted in for improved engine performance and handling.[30]

Differences in testing standards edit

Identical vehicles can have varying fuel consumption figures listed depending upon the testing methods of the jurisdiction.[31]

Lexus IS 250 – petrol 2.5 L 4GR-FSE V6, 204 hp (153 kW), 6 speed automatic, rear wheel drive

  • Australia (L/100 km) – 'combined' 9.1, 'urban' 12.7, 'extra-urban' 7.0[21]
  • Canada (L/100 km) – 'combined' 9.6, 'city' 11.1, 'highway' 7.8[32]
  • European Union (L/100 km) – 'combined' 8.9, 'urban' 12.5, 'extra-urban' 6.9[22]
  • United States (L/100 km) – 'combined' 9.8, 'city' 11.2, 'highway' 8.1[23]

Energy considerations edit

Since the total force opposing the vehicle's motion (at constant speed) multiplied by the distance through which the vehicle travels represents the work that the vehicle's engine must perform, the study of fuel economy (the amount of energy consumed per unit of distance traveled) requires a detailed analysis of the forces that oppose a vehicle's motion. In terms of physics, Force = rate at which the amount of work generated (energy delivered) varies with the distance traveled, or:

 

Note: The amount of work generated by the vehicle's power source (energy delivered by the engine) would be exactly proportional to the amount of fuel energy consumed by the engine if the engine's efficiency is the same regardless of power output, but this is not necessarily the case due to the operating characteristics of the internal combustion engine.

For a vehicle whose source of power is a heat engine (an engine that uses heat to perform useful work), the amount of fuel energy that a vehicle consumes per unit of distance (level road) depends upon:

  1. The thermodynamic efficiency of the heat engine;
  2. Frictional losses within the drivetrain;
  3. Rolling resistance within the wheels and between the road and the wheels;
  4. Non-motive subsystems powered by the engine, such as air conditioning, engine cooling, and the alternator;
  5. Aerodynamic drag from moving through air;
  6. Energy converted by frictional brakes into waste heat, or losses from regenerative braking in hybrid vehicles;
  7. Fuel consumed while the engine is not providing power but still running, such as while idling, minus the subsystem loads.[33]
 
Energy dissipation in city and highway driving for a mid-size gasoline-powered car

Ideally, a car traveling at a constant velocity on level ground in a vacuum with frictionless wheels could travel at any speed without consuming any energy beyond what is needed to get the car up to speed. Less ideally, any vehicle must expend energy on overcoming road load forces, which consist of aerodynamic drag, tire rolling resistance, and inertial energy that is lost when the vehicle is decelerated by friction brakes. With ideal regenerative braking, the inertial energy could be completely recovered, but there are few options for reducing aerodynamic drag or rolling resistance other than optimizing the vehicle's shape and the tire design. Road load energy or the energy demanded at the wheels, can be calculated by evaluating the vehicle equation of motion over a specific driving cycle.[34] The vehicle powertrain must then provide this minimum energy to move the vehicle and will lose a large amount of additional energy in the process of converting fuel energy into work and transmitting it to the wheels. Overall, the sources of energy loss in moving a vehicle may be summarized as follows:

  • Engine efficiency (20–30%), which varies with engine type, the mass of the automobile and its load, and engine speed (usually measured in RPM).
  • Aerodynamic drag force, which increases roughly by the square of the car's speed, but notes that drag power goes by the cube of the car's speed.
  • Rolling friction.
  • Braking, although regenerative braking captures some of the energy that would otherwise be lost.
  • Losses in the transmission. Manual transmissions can be up to 94% efficient whereas older automatic transmissions may be as low as 70% efficient[35] Automated manual transmissions, which have the same mechanical internals as conventional manual transmissions, will give the same efficiency as a pure manual gearbox plus the added bonus of intelligence selecting optimal shifting points, and/or automated clutch control but manual shifting, as with older semi-automatic transmissions.
  • Air conditioning. The power required for the engine to turn the compressor decreases the fuel-efficiency, though only when in use. This may be offset by the reduced drag of the vehicle compared with driving with the windows down. The efficiency of AC systems gradually deteriorates due to dirty filters etc.; regular maintenance prevents this. The extra mass of the air conditioning system will cause a slight increase in fuel consumption.
  • Power steering. The older hydraulic power steering systems are powered by a hydraulic pump constantly engaged to the engine. Power assistance required for steering is inversely proportional to the vehicle speed so the constant load on the engine from a hydraulic pump reduces fuel efficiency. More modern designs improve fuel efficiency by only activating the power assistance when needed; this is done by using either direct electrical power steering assistance or an electrically powered hydraulic pump.
  • Cooling. The older cooling systems used a constantly engaged mechanical fan to draw air through the radiator at a rate directly related to the engine speed. This constant load reduces efficiency. More modern systems use electrical fans to draw additional air through the radiator when extra cooling is required.
  • Electrical systems. Headlights, battery charging, active suspension, circulating fans, defrosters, media systems, speakers, and other electronics can also significantly increase fuel consumption, as the energy to power these devices causes an increased load on the alternator. Since alternators are commonly only 40–60% efficient, the added load from electronics on the engine can be as high as 3 horsepower (2.2 kW) at any speed including idle. In the FTP 75 cycle test, a 200-watt load on the alternator reduces fuel efficiency by 1.7 mpg.[36] Headlights, for example, consume 110 watts on low and up to 240 watts on high. These electrical loads can cause much of the discrepancy between real-world and EPA tests, which only include the electrical loads required to run the engine and basic climate control.
  • Standby. The energy is needed to keep the engine running while it is not providing power to the wheels, i.e., when stopped, coasting or braking.

Fuel-efficiency decreases from electrical loads are most pronounced at lower speeds because most electrical loads are constant while engine load increases with speed. So at a lower speed, a higher proportion of engine horsepower is used by electrical loads. Hybrid cars see the greatest effect on fuel-efficiency from electrical loads because of this proportional effect.

Fuel economy-boosting technologies edit

Main article: Fuel saving devices

Engine-specific technology edit

Type Technology Explanation Inventor Notes
Engine cycle Replacing petrol engines with diesel engines Reduces brake specific fuel consumption at lower RPM Herbert Akroyd Stuart
Engine combustion strategies Electronic control of the cooling system Optimizes engine running temperature
Stratified Charge combustion Injects fuel into cylinder just before ignition, increasing compression ratio For use in petrol engines
Lean burn combustion Increases air/fuel ratio to reduce throttling losses Chrysler https://www.youtube.com/watch?v=KnNX6gtDyhg
Cooled exhaust gas recirculation (petrol) Reduces throttling losses, heat rejection, chemical dissociation, and specific heat ratio
Cooled exhaust gas recirculation (diesel) Lowers peak combustion temperatures
Atkinson cycle Lengthens power stroke to achieve greater thermal efficiency James Atkinson
 
Atkinson cycle
Variable valve timing and variable valve lift Alters valve lift timing and height for precise control over intake and exhaust William Howe and William Williams (Robert Stephenson and Company) invented the first variable timing valve
Variable geometry turbocharging Optimizes airflow with adjustable vanes to regulate turbocharger's air intake and eliminate turbo lag Garrett (Honeywell)
 
VNT Vanes Open
Twincharging Combines a supercharger with a turbocharger to eliminate turbo lag Lancia For use in small-displacement engines
Gasoline direct injection (GDI) engines Allows for stratified fuel charge and ultra-lean burn Leon Levavasseur
Turbocharged Direct Injection diesel engines Combines direct injection with a turbocharger Volkswagen
Common rail direct injection Increases injection pressure Robert Huber
Piezoelectric diesel injectors Uses multiple injections per engine cycle for increased precision
Cylinder management Shuts off individual cylinders when their power output is not needed
HCCI (Homogeneous Charge Compression Ignition) combustion Allows leaner and higher compression burn https://www.youtube.com/watch?v=B8CnYljXAS0
Scuderi engine Eliminates recompression losses Carmelo J. Scuderi
 
Scuderi engine
Compound engines (6-stroke engine or turbo-compound engine) Recovers exhaust energy
Two-stroke diesel engines Increases power to weight ratio Charles F. Kettering
High-efficiency gas turbine engines Increases power to weight ratio
Turbosteamer Uses heat from the engine to spin a mini turbine to generate power Raymond Freymann (BMW)
Stirling hybrid battery vehicle Increases thermal efficiency Still largely theoretical, although prototypes have been produced by Dean Kamen
Time-optimized piston path Captures energy from gases in the cylinders at their highest temperatures
Engine internal losses Downsized engines with a supercharger or a turbocharger Reduces engine displacement while maintaining sufficient torque Saab, starting with the 99 in 1978.
 
2014-Global-Turbo-Forecast
Lower-friction lubricants (engine oil, transmission fluid, axle fluid) Reduces energy lost to friction
Lower viscosity engine oils Reduces hydrodynamic friction and energy required to circulate
Variable displacement oil pump Avoids excessive flow rate at high engine speed
Electrifying engine accessories (water pump, power steering pump, and air conditioner compressor) Sends more engine power to the transmission or reduces the fuel required for the same traction power
Roller type cam, low friction coating on piston skirt and optimizing load-bearing surface, e.g. camshaft bearing and connective rods. Reduces engine frictions
Engine running conditions Coolant additives Increases the thermal efficiency of the cooling system
Increasing the number of gearbox ratios in manual gearboxes Lowers the engine rpm at cruise
Reducing the volume of water-based cooling systems Engine reaches its efficient operating temperature more quickly
Start-stop system Automatically shuts off engine when vehicle is stopped, reducing idle time
Downsized engines with an electric drive system and battery Avoids low-efficiency idle and power conditions

Other vehicle technologies edit

Type Technology Explanation Inventor Notes
Transmission losses Continuously variable transmission (CVT) Enables engine to run at its most efficient RPM For use in automatic gearboxes
Locking torque converters in automatic transmissions Reduces slip and power losses in the converter
Rolling resistance Lighter construction materials (aluminum, fiberglass, plastic, high-strength steel, and carbon fiber) Reduces vehicle weight
Increasing tire pressure Lowers tire deformation underweight
Replacing tires with low rolling resistance (LRR) models Lowers rolling resistance[37]
Series parallel hybrid Using an electric motor for the base power and an IC engine for assists and boosts, when needed Decreases fuel consumption by running the petrol engine only when needed, in this way also environmentally friendly. TRW
Energy saving Lighter materials for moving parts (pistons, crankshaft, gears, and alloy wheels) Reduces the energy required to move parts
Regenerative braking Captures kinetic energy while braking Louis Antoine Kriéger For use in hybrid or electric vehicles
Recapturing waste heat from the exhaust system Converts heat energy into electricity using thermoelectric cooling Jean Charles Athanase Peltier
Regenerative shock absorbers Recaptures wasted energy in the vehicle suspension[38] Levant Power
Traffic management Active highway management Matches speed limits and vehicles allowed to join motorways with traffic density to maintain traffic throughput
Vehicle electronic control systems that automatically maintain distances between vehicles on motorways Reduces ripple back braking and consequent re-acceleration

Future technologies edit

Technologies that may improve fuel efficiency, but are not yet on the market, include:

  • HCCI (Homogeneous Charge Compression Ignition) combustion
  • Scuderi engine
  • Compound engines
  • Two-stroke diesel engines
  • High-efficiency gas turbine engines
  • BMW's Turbosteamer – using the heat from the engine to spin a mini turbine to generate power
  • Vehicle electronic control systems that automatically maintain distances between vehicles on motorways/freeways that reduce ripple back braking, and consequent re-acceleration.
  • Time-optimized piston path, to capture energy from hot gases in the cylinders when they are at their highest temperatures[citation needed]
  • sterling hybrid battery vehicle

Many aftermarket consumer products exist that are purported to increase fuel economy; many of these claims have been discredited. In the United States, the Environmental Protection Agency maintains a list of devices that have been tested by independent laboratories and makes the test results available to the public.[39]

Fuel economy maximizing behaviors edit

Main article: Fuel economy-maximizing behaviors

Governments, various environmentalist organizations, and companies like Toyota and Shell Oil Company have historically urged drivers to maintain adequate air pressure in tires and careful acceleration/deceleration habits. Keeping track of fuel efficiency stimulates fuel economy-maximizing behavior.[40]

A five-year partnership between Michelin and Anglian Water shows that 60,000 liters of fuel can be saved on tire pressure. The Anglian Water fleet of 4,000 vans and cars are now lasting their full lifetime. This shows the impact that tire pressures have on the fuel efficiency.[41]

Fuel economy as part of quality management regimes edit

Environmental management systems EMAS, as well as good fleet management, includes record-keeping of the fleet fuel consumption. Quality management uses those figures to steer the measures acting on the fleets. This is a way to check whether procurement, driving, and maintenance in total have contributed to changes in the fleet's overall consumption.

Fuel economy standards and testing procedures edit

Gasoline new passenger car fuel efficiency
Country 2004 average Requirement
2004 2005 2008 Later
People's Republic of China[42] 6.9 L/100 km 6.9 L/100 km 6.1 L/100 km
United States 24.6 mpg (9.5 L/100 km) (cars and trucks)* 27 mpg (8.7 L/100 km) (cars only)* 35 mpg (6.7 L/100 km) (Model Year 2020, cars & light trucks)
European Union 4.1 L/100 km (2020, NEDC)
Japan[14] 6.7 L/100 km CAFE eq (2010)
Australia[14] 8.08 L/100 km CAFE eq (2002) none none (as of March 2019)[43]

* highway ** combined

Australia edit

From October 2008, all new cars had to be sold with a sticker on the windscreen showing the fuel consumption and the CO2 emissions.[44] Fuel consumption figures are expressed as urban, extra urban and combined, measured according to ECE Regulations 83 and 101 – which are the based on the European driving cycle; previously, only the combined number was given.

Australia also uses a star rating system, from one to five stars, that combines greenhouse gases with pollution, rating each from 0 to 10 with ten being best. To get 5 stars a combined score of 16 or better is needed, so a car with a 10 for economy (greenhouse) and a 6 for emission or 6 for economy and 10 for emission, or anything in between would get the highest 5 star rating.[45] The lowest rated car is the Ssangyong Korrando with automatic transmission, with one star, while the highest rated was the Toyota Prius hybrid. The Fiat 500, Fiat Punto and Fiat Ritmo as well as the Citroen C3 also received 5 stars.[46] The greenhouse rating depends on the fuel economy and the type of fuel used. A greenhouse rating of 10 requires 60 or less grams of CO2 per km, while a rating of zero is more than 440 g/km CO2. The highest greenhouse rating of any 2009 car listed is the Toyota Prius, with 106 g/km CO2 and 4.4 L/100 km (64 mpg‑imp; 53 mpg‑US). Several other cars also received the same rating of 8.5 for greenhouse. The lowest rated was the Ferrari 575 at 499 g/km CO2 and 21.8 L/100 km (13.0 mpg‑imp; 10.8 mpg‑US). The Bentley also received a zero rating, at 465 g/km CO2. The best fuel economy of any year is the 2004–2005 Honda Insight, at 3.4 L/100 km (83 mpg‑imp; 69 mpg‑US).

Canada edit

Vehicle manufacturers follow a controlled laboratory testing procedure to generate the fuel consumption data that they submit to the Government of Canada. This controlled method of fuel consumption testing, including the use of standardized fuels, test cycles and calculations, is used instead of on-road driving to ensure that all vehicles are tested under identical conditions and that the results are consistent and repeatable.

Selected test vehicles are "run in" for about 6,000 km before testing. The vehicle is then mounted on a chassis dynamometer programmed to take into account the aerodynamic efficiency, weight and rolling resistance of the vehicle. A trained driver runs the vehicle through standardized driving cycles that simulate trips in the city and on the highway. Fuel consumption ratings are derived from the emissions generated during the driving cycles.[47]

THE 5 CYCLE TEST:

  1. The city test simulates urban driving in stop-and-go traffic with an average speed of 34 km/h and a top speed of 90 km/h. The test runs for approximately 31 minutes and includes 23 stops. The test begins from a cold engine start, which is similar to starting a vehicle after it has been parked overnight during the summer. The final phase of the test repeats the first eight minutes of the cycle but with a hot engine start. This simulates restarting a vehicle after it has been warmed up, driven and then stopped for a short time. Over five minutes of test time are spent idling, to represent waiting at traffic lights. The ambient temperature of the test cell starts at 20 °C and ends at 30 °C.
  2. The highway test simulates a mixture of open highway and rural road driving, with an average speed of 78 km/h and a top speed of 97 km/h. The test runs for approximately 13 minutes and does not include any stops. The test begins from a hot engine start. The ambient temperature of the test cell starts at 20 °C and ends at 30 °C.
  3. In the cold temperature operation test, the same driving cycle is used as in the standard city test, except that the ambient temperature of the test cell is set to −7 °C.
  4. In the air conditioning test, the ambient temperature of the test cell is raised to 35 °C. The vehicle's climate control system is then used to lower the internal cabin temperature. Starting with a warm engine, the test averages 35 km/h and reaches a maximum speed of 88 km/h. Five stops are included, with idling occurring 19% of the time.
  5. The high speed/quick acceleration test averages 78 km/h and reaches a top speed of 129 km/h. Four stops are included and brisk acceleration maximizes at a rate of 13.6 km/h per second. The engine begins warm and air conditioning is not used. The ambient temperature of the test cell is constantly 25 °C.

Tests 1, 3, 4, and 5 are averaged to create the city driving fuel consumption rate.

Tests 2, 4, and 5 are averaged to create the highway driving fuel consumption rate.[47]

Europe edit

 
Irish fuel economy label
Main article: New European Driving Cycle

In the European Union, passenger vehicles are commonly tested using two drive cycles, and corresponding fuel economies are reported as "urban" and "extra-urban", in liters per 100 km and (in the UK) in miles per imperial gallon.

The urban economy is measured using the test cycle known as ECE-15, first introduced in 1970 by EC Directive 70/220/EWG and finalized by EEC Directive 90/C81/01 in 1999. It simulates a 4,052 m (2.518 mile) urban trip at an average speed of 18.7 km/h (11.6 mph) and at a maximum speed of 50 km/h (31 mph).

The extra-urban driving cycle or EUDC lasts 400 seconds (6 minutes 40 seconds) at an average speed 62.6 km/h (39 mph) and a top speed of 120 km/h (74.6 mph).[48]

EU fuel consumption numbers are often considerably lower than corresponding US EPA test results for the same vehicle. For example, the 2011 Honda CR-Z with a six-speed manual transmission is rated 6.1/4.4 L/100 km in Europe[49] and 7.6/6.4 L/100 km (31/37 mpg ) in the United States.[50]

In the European Union advertising has to show carbon dioxide (CO2)-emission and fuel consumption data in a clear way as described in the UK Statutory Instrument 2004 No 1661.[51] Since September 2005 a color-coded "Green Rating" sticker has been available in the UK, which rates fuel economy by CO2 emissions: A: <= 100 g/km, B: 100–120, C: 121–150, D: 151–165, E: 166–185, F: 186–225, and G: 226+. Depending on the type of fuel used, for gasoline A corresponds to about 4.1 L/100 km (69 mpg‑imp; 57 mpg‑US) and G about 9.5 L/100 km (30 mpg‑imp; 25 mpg‑US).[52] Ireland has a very similar label, but the ranges are slightly different, with A: <= 120 g/km, B: 121–140, C: 141–155, D: 156–170, E: 171–190, F: 191–225, and G: 226+.[53] From 2020, EU requires manufacturers to average 95 g/km CO2 emission or less, or pay an excess emissions premium.[54]

In the UK the ASA (Advertising standards agency) have claimed that fuel consumption figures are misleading. Often the case with European vehicles as the MPG (miles per gallon) figures that can be advertised are often not the same as "real world" driving.

The ASA have said that car manufacturers can use "cheats" to prepare their vehicles for their compulsory fuel efficiency and emissions tests in a way set out to make themselves look as "clean" as possible. This practice is common in gasoline and diesel vehicle tests, but hybrid and electric vehicles are not immune as manufacturers apply these techniques to fuel efficiency.

Car experts[who?] also assert that the official MPG figures given by manufacturers do not represent the true MPG values from real-world driving.[55] Websites have been set up to show the real-world MPG figures, based on crowd-sourced data from real users, vs the official MPG figures.[56]

The major loopholes in the current EU tests allow car manufacturers a number of "cheats" to improve results. Car manufacturers can:

  • Disconnect the alternator, thus no energy is used to recharge the battery;
  • Use special lubricants that are not used in production cars, in order to reduce friction;
  • Turn off all electrical gadgets i.e. Air Con/Radio;
  • Adjust brakes or even disconnect them to reduce friction;
  • Tape up cracks between body panels and windows to reduce air resistance;
  • Remove Wing mirrors.[57]

According to the results of a 2014 study by the International Council on Clean Transportation (ICCT), the gap between official and real-world fuel-economy figures in Europe has risen to about 38% in 2013 from 10% in 2001. The analysis found that for private cars, the difference between on-road and official CO2 values rose from around 8% in 2001 to 31% in 2013, and 45% for company cars in 2013. The report is based on data from more than half a million private and company vehicles across Europe. The analysis was prepared by the ICCT together with the Netherlands Organization for Applied Scientific Research (TNO), and the German Institut für Energie- und Umweltforschung Heidelberg (IFEU).[58]

In 2018 update of the ICCT data the difference between the official and real figures was again 38%.[59]

Japan edit

The evaluation criteria used in Japan reflects driving conditions commonly found, as the typical Japanese driver does not drive as fast as other regions internationally (Speed limits in Japan).

10–15 mode edit

The 10–15 mode driving cycle test is the official fuel economy and emission certification test for new light duty vehicles in Japan. Fuel economy is expressed in km/L (kilometers per liter) and emissions are expressed in g/km. The test is carried out on a dynamometer and consist of 25 tests which cover idling, acceleration, steady running and deceleration, and simulate typical Japanese urban and/or expressway driving conditions. The running pattern begins with a warm start, lasts for 660 seconds (11 minutes) and runs at speeds up to 70 km/h (43.5 mph).[60][61] The distance of the cycle is 6.34 km (3.9 mi), average speed of 25.6 km/h (15.9 mph), and duration 892 seconds (14.9 minutes), including the initial 15 mode segment.[61]

JC08 edit

A new more demanding test, called the JC08, was established in December 2006 for Japan's new standard that goes into effect in 2015, but it is already being used by several car manufacturers for new cars. The JC08 test is significantly longer and more rigorous than the 10–15 mode test. The running pattern with JC08 stretches out to 1200 seconds (20 minutes), and there are both cold and warm start measurements and top speed is 82 km/h (51.0 mph). The economy ratings of the JC08 are lower than the 10–15 mode cycle, but they are expected to be more real world.[60] The Toyota Prius became the first car to meet Japan's new 2015 Fuel Economy Standards measured under the JC08 test.[62]

New Zealand edit

Starting on 7 April 2008 all cars of up to 3.5 tonnes GVW sold other than private sale need to have a fuel economy sticker applied (if available) that shows the rating from one half star to six stars with the most economic cars having the most stars and the more fuel hungry cars the least, along with the fuel economy in L/100 km and the estimated annual fuel cost for driving 14,000 km (at present fuel prices). The stickers must also appear on vehicles to be leased for more than 4 months. All new cars currently rated range from 6.9 L/100 km (41 mpg‑imp; 34 mpg‑US) to 3.8 L/100 km (74 mpg‑imp; 62 mpg‑US) and received respectively from 4.5 to 5.5 stars.[63]

Saudi Arabia edit

The Kingdom of Saudi Arabia announced new light-duty vehicle fuel economy standards in November 2014 which became effective 1 January 2016 and will be fully phased in by 1 January 2018 (Saudi Standards regulation SASO-2864). A review of the targets will be carried by December 2018, at which time targets for 2021–2025 will be set.

United States edit

 
Motor vehicle fuel economy from 1949 to 2021

US Energy Tax Act edit

Main article: Energy Tax Act

The Energy Tax Act of 1978[64] in the US established a gas guzzler tax on the sale of new model year vehicles whose fuel economy fails to meet certain statutory levels. The tax applies only to cars (not trucks) and is collected by the IRS. Its purpose is to discourage the production and purchase of fuel-inefficient vehicles. The tax was phased in over ten years with rates increasing over time. It applies only to manufacturers and importers of vehicles, although presumably some or all of the tax is passed along to automobile consumers in the form of higher prices. Only new vehicles are subject to the tax, so no tax is imposed on used car sales. The tax is graduated to apply a higher tax rate for less-fuel-efficient vehicles. To determine the tax rate, manufacturers test all the vehicles at their laboratories for fuel economy. The US Environmental Protection Agency confirms a portion of those tests at an EPA lab.

In some cases, this tax may apply only to certain variants of a given model; for example, the 2004–2006 Pontiac GTO (captive import version of the Holden Monaro) did incur the tax when ordered with the four-speed automatic transmission, but did not incur the tax when ordered with the six-speed manual transmission.[65]

EPA testing procedure through 2007 edit

 
The "city" or Urban Dynamometer Driving Schedule (UDDS) used in the EPA Federal Test Procedure
 
The Highway Fuel Economy Driving Cycle (HWFET) used in the EPA Federal Test Procedure

Two separate fuel economy tests simulate city driving and highway driving: the "city" driving program or Urban Dynamometer Driving Schedule or (UDDS) or FTP-72 is defined in 40 CFR 86.I and consists of starting with a cold engine and making 23 stops over a period of 31 minutes for an average speed of 20 mph (32 km/h) and with a top speed of 56 mph (90 km/h).

The "highway" program or Highway Fuel Economy Driving Schedule (HWFET) is defined in 40 CFR 600.I and uses a warmed-up engine and makes no stops, averaging 48 mph (77 km/h) with a top speed of 60 mph (97 km/h) over a 10-mile (16 km) distance. A weighted average of city (55%) and highway (45%) fuel economies is used to determine the combined rating and guzzler tax.[66][67][68] This rating is what is also used for light-duty vehicle corporate average fuel economy regulations.

The procedure has been updated to FTP-75, adding a "hot start" cycle which repeats the "cold start" cycle after a 10-minute pause.

Because EPA figures had almost always indicated better efficiency than real-world fuel-efficiency, the EPA has modified the method starting with 2008. Updated estimates are available for vehicles back to the 1985 model year.[66][69]

EPA testing procedure: 2008 and beyond edit

 
2008 Monroney sticker highlights fuel economy.

US EPA altered the testing procedure effective MY2008 which adds three new Supplemental Federal Test Procedure (SFTP) tests to include the influence of higher driving speed, harder acceleration, colder temperature and air conditioning use.[70]

SFTP US06 is a high speed/quick acceleration loop that lasts 10 minutes, covers 8 miles (13 km), averages 48 mph (77 km/h) and reaches a top speed of 80 mph (130 km/h). Four stops are included, and brisk acceleration maximizes at a rate of 8.46 mph (13.62 km/h) per second. The engine begins warm and air conditioning is not used. Ambient temperature varies between 68 °F (20 °C) to 86 °F (30 °C).

SFTO SC03 is the air conditioning test, which raises ambient temperatures to 95 °F (35 °C), and puts the vehicle's climate control system to use. Lasting 9.9 minutes, the 3.6-mile (5.8 km) loop averages 22 mph (35 km/h) and maximizes at a rate of 54.8 mph (88.2 km/h). Five stops are included, idling occurs 19 percent of the time and acceleration of 5.1 mph per second is achieved. Engine temperatures begin warm.

Lastly, a cold temperature cycle uses the same parameters as the current city loop, except that ambient temperature is set to 20 °F (−7 °C).

EPA tests for fuel economy do not include electrical load tests beyond climate control, which may account for some of the discrepancy between EPA and real world fuel-efficiency. A 200 W electrical load can produce a 0.4 km/L (0.94 mpg) reduction in efficiency on the FTP 75 cycle test.[36]

Beginning with model year 2017 the calculation method changed to improve the accuracy of the estimated 5-cycle city and highway fuel economy values derived from just the FTP and HFET tests, with lower uncertainty for fuel efficient vehicles.[71]

Electric vehicles and hybrids edit

 
2010 Monroney sticker for a plug-in hybrid showing fuel economy in all-electric mode and gasoline-only mode

Following the efficiency claims made for vehicles such as Chevrolet Volt and Nissan Leaf, the National Renewable Energy Laboratory recommended to use EPA's new vehicle fuel efficiency formula that gives different values depending on fuel used.[72] In November 2010 the EPA introduced the first fuel economy ratings in the Monroney stickers for plug-in electric vehicles.

For the fuel economy label of the Chevy Volt plug-in hybrid EPA rated the car separately for all-electric mode expressed in miles per gallon gasoline equivalent (MPG-e) and for gasoline-only mode expressed in conventional miles per gallon. EPA also estimated an overall combined city/highway gas-electricity fuel economy rating expressed in miles per gallon gasoline equivalent (MPG-e). The label also includes a table showing fuel economy and electricity consumed for five different scenarios: 30 miles (48 km), 45 miles (72 km), 60 miles (97 km) and 75 miles (121 km) driven between a full charge, and a never charge scenario. This information was included to make the consumers aware of the variability of the fuel economy outcome depending on miles driven between charges. Also the fuel economy for a gasoline-only scenario (never charge) was included. For electric-only mode the energy consumption estimated in kWh per 100 miles (160 km) is also shown.[73][74]

 
2010 Monroney label showing the EPA's combined city/highway fuel economy equivalent for an all-electric car, in this case a 2010 Nissan Leaf

For the fuel economy label of the Nissan Leaf electric car EPA rated the combined fuel economy in terms of miles per gallon gasoline equivalent, with a separate rating for city and highway driving. This fuel economy equivalence is based on the energy consumption estimated in kWh per 100 miles, and also shown in the Monroney label.[75]

In May 2011, the National Highway Traffic Safety Administration (NHTSA) and EPA issued a joint final rule establishing new requirements for a fuel economy and environment label that is mandatory for all new passenger cars and trucks starting with model year 2013, and voluntary for 2012 models. The ruling includes new labels for alternative fuel and alternative propulsion vehicles available in the US market, such as plug-in hybrids, electric vehicles, flexible-fuel vehicles, hydrogen fuel cell vehicle, and natural gas vehicles.[76][77] The common fuel economy metric adopted to allow the comparison of alternative fuel and advanced technology vehicles with conventional internal combustion engine vehicles is miles per gallon of gasoline equivalent (MPGe). A gallon of gasoline equivalent means the number of kilowatt-hours of electricity, cubic feet of compressed natural gas (CNG), or kilograms of hydrogen that is equal to the energy in a gallon of gasoline.[76]

The new labels also include for the first time an estimate of how much fuel or electricity it takes to drive 100 miles (160 km), providing US consumers with fuel consumption per distance traveled, the metric commonly used in many other countries. EPA explained that the objective is to avoid the traditional miles per gallon metric that can be potentially misleading when consumers compare fuel economy improvements, and known as the "MPG illusion"[78] – this illusion arises because the reciprocal (i.e. non-linear) relationship between cost (equivalently, volume of fuel consumed) per unit distance driven and MPG value means that differences in MPG values are not directly meaningful – only ratios are (in mathematical terms, the reciprocal function does not commute with addition and subtraction; in general, a difference in reciprocal values is not equal to the reciprocal of their difference). It has been claimed that many consumers are unaware of this, and therefore compare MPG values by subtracting them, which can give a misleading picture of relative differences in fuel economy between different pairs of vehicles – for instance, an increase from 10 to 20 MPG corresponds to a 100% improvement in fuel economy, whereas an increase from 50 to 60 MPG is only a 20% improvement, although in both cases the difference is 10 MPG.[79] The EPA explained that the new gallons-per-100-miles metric provides a more accurate measure of fuel efficiency[76][80] – notably, it is equivalent to the normal metric measurement of fuel economy, liters per 100 kilometers (L/100 km).

CAFE standards edit

 
Curve of average car mileage for model years between 1978 and 2014
Main article: Corporate Average Fuel Economy

The Corporate Average Fuel Economy (CAFE) regulations in the United States, first enacted by Congress in 1975,[81] are federal regulations intended to improve the average fuel economy of cars and light trucks (trucks, vans and sport utility vehicles) sold in the US in the wake of the 1973 Arab Oil Embargo. Historically, it is the sales-weighted average fuel economy of a manufacturer's fleet of current model year passenger cars or light trucks, manufactured for sale in the United States. Under Truck CAFE standards 2008–2011 this changes to a "footprint" model where larger trucks are allowed to consume more fuel. The standards were limited to vehicles under a certain weight, but those weight classes were expanded in 2011.

Federal and state regulations edit

The Clean Air Act of 1970 prohibited states from establishing their own air pollution standards. However, the legislation authorized the EPA to grant a waiver to California, allowing the state to set higher standards.[82] The law provides a “piggybacking” provision that allows other states to adopt vehicle emission limits that are the same as California's.[83] California's waivers were routinely granted until 2007, when the George W. Bush administration rejected the state's bid to adopt global warming pollution limits for cars and light trucks.[84] California and 15 other states that were trying to put in place the same emissions standards sued in response.[85] The case was tied up in court until the Obama administration reversed the policy in 2009 by granting the waiver.[86]

In August 2012, President Obama announced new standards for American-made automobiles of an average of 54.5 miles per gallon by the year 2025.[87][88] In April 2018, EPA Administrator Scott Pruitt announced that the Trump administration planned to roll back the 2012 federal standards and would also seek to curb California's authority to set its own standards.[82] Although the Trump administration was reportedly considering a compromise to allow state and national standards to stay in place,[89] on 21 February 2019 the White House declared that it had abandoned these negotiations.[90] A government report subsequently found that, in 2019, new light-duty vehicle fuel economy fell 0.2 miles per gallon (to 24.9 miles per gallon) and pollution increased 3 grams per mile traveled (to 356 grams per mile). A decrease in fuel economy and an increase in pollution had not occurred for the previous five years.[91] The Obama-era rule was officially rolled back on 31 March 2020 during the Trump administration,[92] but the rollback was reversed on 20 December 2021 during the Biden administration.[93]

Fuel economy of trucks edit

Trucks are usually bought as an investment good. They are meant to earn money. As the Diesel fuel burnt in heavy trucks accounts for around 30%[94] of the total costs for a freight forwarding company there is always a lot of interest in both the haulage industry and the truck builder industry to strive for best fuel economy. For truck buyers the fuel economy measured by standard procedures is only a first guideline. Professional trucking companies measure the fuel economy of their trucks and truck fleets in real usage. Fuel economy of trucks in real usage is determined by four important factors:[94] The truck technology that is constantly improved by the various OEMs. The driver's driving style contributes a lot to the real fuel economy (different from the test cycles where a standard driving style is used). The maintenance condition of the vehicle influences the fuel efficiency – again different from standardized procedures where the trucks are always presented in flawless condition. Last but not least the usage of the vehicle influences the fuel consumption: Hilly roads and heavy loads will increase the fuel consumption of a vehicle.

Effect on pollution edit

Further information: Gas-guzzler and Vehicle Efficiency Initiative

Fuel efficiency directly affects emissions causing pollution by affecting the amount of fuel used. However, it also depends on the fuel source used to drive the vehicle concerned. Cars for example, can run on a number of fuel types other than gasoline, such as natural gas, LPG or biofuel or electricity which creates various quantities of atmospheric pollution.

A kilogram of carbon, whether contained in petrol, diesel, kerosene, or any other hydrocarbon fuel in a vehicle, leads to approximately 3.6 kg of CO2 emissions.[95] Due to the carbon content of gasoline, its combustion emits 2.3 kg/L (19.4 lb/US gal) of CO2; since diesel fuel is more energy dense per unit volume, diesel emits 2.6 kg/L (22.2 lb/US gal).[95] This figure is only the CO2 emissions of the final fuel product and does not include additional CO2 emissions created during the drilling, pumping, transportation and refining steps required to produce the fuel. Additional measures to reduce overall emission includes improvements to the efficiency of air conditioners, lights and tires.

Unit conversions edit

US Gallons
  • 1 mpg ≈ 0.425 km/L
  • 235.2/mpg ≈ L/100 km
  • 1 mpg ≈ 1.201 mpg (imp)
Imperial gallons
  • 1 mpg ≈ 0.354 km/L
  • 282/mpg ≈ L/100 km
  • 1 mpg ≈ 0.833 mpg (US)

Conversion from mpg edit

mpg (imp) mpg (US) km/L L/100 km
5 4.2 1.8 56.5
10 8.3 3.5 28.2
15 12.5 5.3 18.8
20 16.7 7.1 14.1
25 20.8 8.9 11.3
30 25.0 10.6 9.4
35 29.1 12.4 8.1
40 33.3 14.2 7.1
45 37.5 15.9 6.3
50 41.6 17.7 5.6
55 45.8 19.5 5.1
60 50.0 21.2 4.7
65 54.1 23.0 4.3
70 58.3 24.8 4.0
75 62.5 26.6 3.8
80 66.6 28.3 3.5
85 70.8 30.1 3.3
90 74.9 31.9 3.1
95 79.1 33.6 3.0
100 83.3 35.4 2.8
mpg (US) mpg (imp) km/L L/100 km
5 6.0 2.1 47.0
10 12.0 4.3 23.5
15 18.0 6.4 15.7
20 24.0 8.5 11.8
25 30.0 10.6 9.4
30 36.0 12.8 7.8
35 42.0 14.9 6.7
40 48.0 17.0 5.9
45 54.0 19.1 5.2
50 60.0 21.3 4.7
55 66.1 23.4 4.3
60 72.1 25.5 3.9
65 78.1 27.6 3.6
70 84.1 29.8 3.4
75 90.1 31.9 3.1
80 96.1 34.0 2.9
85 102.1 36.1 2.8
90 108.1 38.3 2.6
95 114.1 40.4 2.5
100 120.1 42.5 2.4

Conversion from km/L and L/100 km edit

L/100 km km/L mpg (US) mpg (imp)
1 100.0 235.2 282.5
2 50.0 117.6 141.2
3 33.3 78.4 94.2
4 25.0 58.8 70.6
5 20.0 47.0 56.5
6 16.7 39.2 47.1
7 14.3 33.6 40.4
8 12.5 29.4 35.3
9 11.1 26.1 31.4
10 10.0 23.5 28.2
15 6.7 15.7 18.8
20 5.0 11.8 14.1
25 4.0 9.4 11.3
30 3.3 7.8 9.4
35 2.9 6.7 8.1
40 2.5 5.9 7.1
45 2.2 5.2 6.3
50 2.0 4.7 5.6
55 1.8 4.3 5.1
60 1.7 3.9 4.7
km/L L/100 km mpg (US) mpg (imp)
5 20.0 11.8 14.1
10 10.0 23.5 28.2
15 6.7 35.3 42.4
20 5.0 47.0 56.5
25 4.0 58.8 70.6
30 3.3 70.6 84.7
35 2.9 82.3 98.9
40 2.5 94.1 113.0
45 2.2 105.8 127.1
50 2.0 117.6 141.2
55 1.8 129.4 155.4
60 1.7 141.1 169.5
65 1.5 152.9 183.6
70 1.4 164.7 197.7
75 1.3 176.4 211.9
80 1.3 188.2 226.0
85 1.2 199.9 240.1
90 1.1 211.7 254.2
95 1.1 223.5 268.4
100 1.0 235.2 282.5

See also edit

Annotations edit

  1. ^ Specifically, the production-weighted harmonic mean
  2. ^ The 2.2% drop figure was calculated by finding daily consumption to be 9,299,684 barrels of petroleum. Obtain 1973's petroleum consumption from transportation sector at 2.1e from the Energy Consumption by Sector section, then convert to barrels using A1 in the Thermal Conversion Factors section (assume "conventional motor gasoline" since ethanol-based or purportedly smog-reducing gas was not common in 1973).[17]

References edit

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  3. ^ "Fuel Consumption Ratings". Government of Canada. January 2011. Retrieved 8 June 2011.
  4. ^ . Archived from the original on 3 September 2012. Retrieved 6 November 2012.
  5. ^ "The Passenger Car (Fuel Consumption and CO2 Emissions Information) Regulations 2001". 2001. Retrieved 11 November 2014.
  6. ^ The New Fuel Economy Label at FuelEconomy.gov
  7. ^ "Highlights of the Automotive Trends Report". EPA.gov. U.S. Environmental Protection Agency (EPA). 12 December 2022. from the original on 2 September 2023.
  8. ^ Cazzola, Pierpaolo; Paoli, Leonardo; Teter, Jacob (November 2023). "Trends in the Global Vehicle Fleet 2023 / Managing the SUV Shift and the EV Transition" (PDF). Global Fuel Economy Initiative (GFEI). p. 3. doi:10.7922/G2HM56SV. (PDF) from the original on 26 November 2023.
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  13. ^ Myth: Cars are becoming more fuel efficient. Ptua.org.au. Retrieved 21 September 2011.
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  20. ^ (PDF). Federal Highway Administration: 76. Archived from the original (PDF) on 4 March 2013. Retrieved 17 September 2014. {{cite journal}}: Cite journal requires |journal= (help)
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  22. ^ a b IS 250 Kraftstoffverbrauch kombiniert 8,9 L/100 km (innerorts 12,5 L/ außerorts 6,9 L) bei CO2-Emissionen von 209 g/km nach dem vorgeschriebenen EU-Messverfahren . Archived from the original on 2 April 2010. Retrieved 22 April 2010.
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External links edit

January 01, 1970
fuel, economy, automobiles, fuel, economy, automobile, relates, distance, traveled, vehicle, amount, fuel, consumed, consumption, expressed, terms, volume, fuel, travel, distance, distance, traveled, unit, volume, fuel, consumed, since, fuel, consumption, vehi. The fuel economy of an automobile relates to the distance traveled by a vehicle and the amount of fuel consumed Consumption can be expressed in terms of the volume of fuel to travel a distance or the distance traveled per unit volume of fuel consumed Since fuel consumption of vehicles is a significant factor in air pollution and since the importation of motor fuel can be a large part of a nation s foreign trade many countries impose requirements for fuel economy Fuel consumption monitor from a 2006 Honda Airwave The displayed fuel economy is 18 1 km L 5 5 L 100 km 43 mpg US A Briggs and Stratton Flyer from 1916 Originally an experiment in creating a fuel saving automobile in the United States the vehicle weighed only 135 lb 61 2 kg and was an adaptation of a small gasoline engine originally designed to power a bicycle 1 Different methods are used to approximate the actual performance of the vehicle The energy in fuel is required to overcome various losses wind resistance tire drag and others encountered while propelling the vehicle and in providing power to vehicle systems such as ignition or air conditioning Various strategies can be employed to reduce losses at each of the conversions between the chemical energy in the fuel and the kinetic energy of the vehicle Driver behavior can affect fuel economy maneuvers such as sudden acceleration and heavy braking waste energy Electric cars do not directly burn fuel and so do not have fuel economy per se but equivalence measures such as miles per gallon gasoline equivalent have been created to attempt to compare them Contents 1 Quantities and units of measure 2 Statistics 2 1 Speed and fuel economy studies 2 2 Discussion of statistics 2 3 Differences in testing standards 3 Energy considerations 3 1 Fuel economy boosting technologies 3 1 1 Engine specific technology 3 1 2 Other vehicle technologies 3 1 3 Future technologies 3 2 Fuel economy maximizing behaviors 3 3 Fuel economy as part of quality management regimes 4 Fuel economy standards and testing procedures 4 1 Australia 4 2 Canada 4 3 Europe 4 4 Japan 4 4 1 10 15 mode 4 4 2 JC08 4 5 New Zealand 4 6 Saudi Arabia 4 7 United States 4 7 1 US Energy Tax Act 4 7 2 EPA testing procedure through 2007 4 7 3 EPA testing procedure 2008 and beyond 4 7 4 Electric vehicles and hybrids 4 7 5 CAFE standards 4 7 6 Federal and state regulations 5 Fuel economy of trucks 6 Effect on pollution 7 Unit conversions 7 1 Conversion from mpg 7 2 Conversion from km L and L 100 km 8 See also 9 Annotations 10 References 11 External linksQuantities and units of measure edit nbsp Conversion from mpg to L 100 km blue U S gallon red imperial gallon The fuel efficiency of motor vehicles can be expressed in multiple ways Fuel consumption is the amount of fuel used per unit distance for example litres per 100 kilometres L 100 km The lower the value the more economic a vehicle is the less fuel it needs to travel a certain distance this is the measure generally used across Europe except the UK Denmark and The Netherlands see below New Zealand Australia and Canada Also in Uruguay Paraguay Guatemala Colombia China and Madagascar citation needed as also in post Soviet space Fuel economy is the distance travelled per unit volume of fuel used for example kilometres per litre km L or miles per gallon MPG where 1 MPG imperial 0 354006 km L The higher the value the more economic a vehicle is the more distance it can travel with a certain volume of fuel This measure is popular in the US and the UK mpg but in Europe India Japan South Korea and Latin America the metric unit km L is used instead The formula for converting to miles per US gallon 3 7854 L from L 100 km is 235 215 x displaystyle textstyle frac 235 215 x nbsp where x displaystyle x nbsp is value of L 100 km For miles per Imperial gallon 4 5461 L the formula is 282 481 x displaystyle textstyle frac 282 481 x nbsp In parts of Europe the two standard measuring cycles for litre 100 km value are urban traffic with speeds up to 50 km h from a cold start and then extra urban travel at various speeds up to 120 km h which follows the urban test A combined figure is also quoted showing the total fuel consumed in divided by the total distance traveled in both tests Fuel economy can be expressed in two ways Units of fuel per fixed distance Generally expressed in liters per 100 kilometers L 100 km used in most European countries China South Africa Australia and New Zealand Irish law allows for the use of miles per imperial gallon alongside liters per 100 kilometers 2 Canadian law requires fuel economy to be measured in both liters per 100 kilometers and miles per imperial gallon 3 4 5 Liters per 100 kilometers may be used alongside miles per imperial gallon in the UK The window sticker on new US cars displays the vehicle s fuel consumption in US gallons per 100 miles in addition to the traditional mpg number 6 A lower number means more efficient while a higher number means less efficient Units of distance per fixed fuel unit Miles per gallon mpg are commonly used in the United States the United Kingdom and Canada alongside L 100 km Kilometers per liter km L are more commonly used elsewhere in the Americas Asia parts of Africa and Oceania In the Levant km 20 L is used known as kilometers per tanaka a metal container which has a volume of twenty liters When mpg is used it is necessary to identify the type of gallon the imperial gallon is 4 54609 liters and the U S gallon is 3 785 liters When using a measure expressed as distance per fuel unit a higher number means more efficient while a lower number means less efficient Conversions of units Miles per US gallon L 100 km 235 m p g U S 1 L 100 k m displaystyle frac 235 rm mpg US rm 1 L 100 km nbsp L 100 km Miles per US gallon 235 L 100 k m 1 m p g U S displaystyle frac 235 rm L 100 km rm 1 mpg US nbsp Miles per Imperial gallon L 100 km 282 m p g I m p 1 L 100 k m displaystyle frac 282 rm mpg Imp rm 1 L 100 km nbsp L 100 km Miles per Imperial gallon 282 L 100 k m 1 m p g I m p displaystyle frac 282 rm L 100 km rm 1 mpg Imp nbsp Miles per US gallon km 20 L 8 5 m p g U S 1 k m 20 L displaystyle rm 8 5 mpg US 1 km 20 L nbsp L 100 km km 20 L 2000 L 100 k m 1 k m 20 L displaystyle frac 2000 rm L 100 km rm 1 km 20 L nbsp Miles per US gallon Miles per Imperial gallon 1 m p g U S 0 8327 m p g I m p displaystyle 1 rm mpg US rm 0 8327 rm mpg Imp nbsp Miles per Imperial gallon Miles per US gallon 1 m p g I m p 1 2001 m p g U S displaystyle 1 rm mpg Imp 1 2001 rm mpg US nbsp Statistics edit nbsp Trucks share of US vehicles produced has tripled since 1975 Though vehicle fuel efficiency has increased within each category the overall trend toward less efficient types of vehicles has offset some of the benefits of greater fuel economy and reduction of carbon dioxide emissions 7 Without the shift towards SUVs energy use per unit distance could have fallen 30 more than it did from 2010 to 2022 8 While the thermal efficiency mechanical output to chemical energy in fuel of petroleum engines has increased since the beginning of the automotive era this is not the only factor in fuel economy The design of automobile as a whole and usage pattern affects the fuel economy Published fuel economy is subject to variation between jurisdiction due to variations in testing protocols One of the first studies to determine fuel economy in the United States was the Mobil Economy Run which was an event that took place every year from 1936 except during World War II to 1968 It was designed to provide real efficient fuel efficiency numbers during a coast to coast test on real roads and with regular traffic and weather conditions The Mobil Oil Corporation sponsored it and the United States Auto Club USAC sanctioned and operated the run In more recent studies the average fuel economy for new passenger car in the United States improved from 17 mpg 13 8 L 100 km in 1978 to more than 22 mpg 10 7 L 100 km in 1982 9 The average a fuel economy for new 2020 model year cars light trucks and SUVs in the United States was 25 4 miles per US gallon 9 3 L 100 km 10 2019 model year cars ex EVs classified as midsize by the US EPA ranged from 12 to 56 mpgUS 20 to 4 2 L 100 km 11 However due to environmental concerns caused by CO2 emissions new EU regulations are being introduced to reduce the average emissions of cars sold beginning in 2012 to 130 g km of CO2 equivalent to 4 5 L 100 km 52 mpgUS 63 mpgimp for a diesel fueled car and 5 0 L 100 km 47 mpgUS 56 mpgimp for a gasoline petrol fueled car 12 The average consumption across the fleet is not immediately affected by the new vehicle fuel economy for example Australia s car fleet average in 2004 was 11 5 L 100 km 20 5 mpgUS 13 compared with the average new car consumption in the same year of 9 3 L 100 km 25 3 mpgUS 14 Speed and fuel economy studies edit nbsp 1997 fuel economy statistics for various US models Fuel economy at steady speeds with selected vehicles was studied in 2010 The most recent study 15 indicates greater fuel efficiency at higher speeds than earlier studies for example some vehicles achieve better fuel economy at 100 km h 62 mph rather than at 70 km h 43 mph 15 although not their best economy such as the 1994 Oldsmobile Cutlass Ciera with the LN2 2 2L engine which has its best economy at 90 km h 56 mph 8 1 L 100 km 29 mpg US and gets better economy at 105 km h 65 mph than at 72 km h 45 mph 9 4 L 100 km 25 mpg US vs 22 mpg US 11 L 100 km The proportion of driving on high speed roadways varies from 4 in Ireland to 41 in the Netherlands When the US National Maximum Speed Law s 55 mph 89 km h speed limit was mandated from 1974 to 1995 there were complaints that fuel economy could decrease instead of increase The 1997 Toyota Celica got better fuel efficiency at 105 km h 65 mph than it did at 65 km h 40 mph 5 41 L 100 km 43 5 mpg US vs 5 53 L 100 km 42 5 mpg US although even better at 60 mph 97 km h than at 65 mph 105 km h 48 4 mpg US 4 86 L 100 km vs 43 5 mpg US 5 41 L 100 km and its best economy 52 6 mpg US 4 47 L 100 km at only 25 mph 40 km h Other vehicles tested had from 1 4 to 20 2 better fuel efficiency at 90 km h 56 mph vs 105 km h 65 mph Their best economy was reached at speeds of 40 to 90 km h 25 to 56 mph see graph 15 Officials hoped that the 55 mph 89 km h limit combined with a ban on ornamental lighting no gasoline sales on Sunday and a 15 cut in gasoline production would reduce total gasoline consumption by 200 000 barrels a day representing a 2 2 drop from annualized 1973 gasoline consumption levels 16 b This was partly based on a belief that cars achieve maximum efficiency between 40 and 50 mph 65 and 80 km h and that trucks and buses were most efficient at 55 mph 89 km h 18 In 1998 the U S Transportation Research Board footnoted an estimate that the 1974 National Maximum Speed Limit NMSL reduced fuel consumption by 0 2 to 1 0 percent 19 Rural interstates the roads most visibly affected by the NMSL accounted for 9 5 of the U S vehicle miles traveled in 1973 20 but such free flowing roads typically provide more fuel efficient travel than conventional roads 21 22 23 Discussion of statistics edit A reasonably modern European supermini and many mid size cars including station wagons may manage motorway travel at 5 L 100 km 47 mpg US 56 mpg imp or 6 5 L 100 km in city traffic 36 mpg US 43 mpg imp with carbon dioxide emissions of around 140 g km An average North American mid size car travels 21 mpg US 11 L 100 km city 27 mpg US 9 L 100 km highway a full size SUV usually travels 13 mpg US 18 L 100 km city and 16 mpg US 15 L 100 km highway Pickup trucks vary considerably whereas a 4 cylinder engined light pickup can achieve 28 mpg 8 L 100 km a V8 full size pickup with extended cabin only travels 13 mpg US 18 L 100 km city and 15 mpg US 15 L 100 km highway The average fuel economy for all vehicles on the road is higher in Europe than the United States because the higher cost of fuel changes consumer behaviour In the UK a gallon of gas without tax would cost US 1 97 but with taxes cost US 6 06 in 2005 The average cost in the United States was US 2 61 24 European built cars are generally more fuel efficient than US vehicles While Europe has many higher efficiency diesel cars European gasoline vehicles are on average also more efficient than gasoline powered vehicles in the USA Most European vehicles cited in the CSI study run on diesel engines which tend to achieve greater fuel efficiency than gas engines Selling those cars in the United States is difficult because of emission standards notes Walter McManus a fuel economy expert at the University of Michigan Transportation Research Institute For the most part European diesels don t meet U S emission standards McManus said in 2007 Another reason why many European models are not marketed in the United States is that labor unions object to having the big 3 import any new foreign built models regardless of fuel economy while laying off workers at home 25 An example of European cars capabilities of fuel economy is the microcar Smart Fortwo cdi which can achieve up to 3 4 L 100 km 69 2 mpg US using a turbocharged three cylinder 41 bhp 30 kW Diesel engine The Fortwo is produced by Daimler AG and is only sold by one company in the United States Furthermore the world record in fuel economy of production cars is held by the Volkswagen Group with special production models labeled 3L of the Volkswagen Lupo and the Audi A2 consuming as little as 3 L 100 km 94 mpg imp 78 mpg US 26 clarification needed Diesel engines generally achieve greater fuel efficiency than petrol gasoline engines Passenger car diesel engines have energy efficiency of up to 41 but more typically 30 and petrol engines of up to 37 3 but more typically 20 A common margin is 25 more miles per gallon for an efficient turbodiesel For example the current model Skoda Octavia using Volkswagen engines has a combined European fuel efficiency of 41 3 mpg US 5 70 L 100 km for the 105 bhp 78 kW petrol engine and 52 3 mpg US 4 50 L 100 km for the 105 bhp 78 kW and heavier diesel engine The higher compression ratio is helpful in raising the energy efficiency but diesel fuel also contains approximately 10 more energy per unit volume than gasoline which contributes to the reduced fuel consumption for a given power output In 2002 the United States had 85 174 776 trucks and averaged 13 5 miles per US gallon 17 4 L 100 km 16 2 mpg imp Large trucks over 33 000 pounds 15 000 kg averaged 5 7 miles per US gallon 41 L 100 km 6 8 mpg imp 27 Truck fuel economy GVWR lbs Number Percentage Average miles per truck fuel economy Percentage of fuel use 6 000 lbs and less 51 941 389 61 00 11 882 17 6 42 70 6 001 10 000 lbs 28 041 234 32 90 12 684 14 3 30 50 Light truck subtotal 79 982 623 93 90 12 163 16 2 73 20 10 001 14 000 lbs 691 342 0 80 14 094 10 5 1 10 14 001 16 000 lbs 290 980 0 30 15 441 8 5 0 50 16 001 19 500 lbs 166 472 0 20 11 645 7 9 0 30 19 501 26 000 lbs 1 709 574 2 00 12 671 7 3 20 Medium truck subtotal 2 858 368 3 40 13 237 8 5 20 26 001 33 000 lbs 179 790 0 20 30 708 6 4 0 90 33 001 lbs and up 2 153 996 2 50 45 739 5 7 20 70 Heavy truck subtotal 2 333 786 2 70 44 581 5 8 21 60 Total 85 174 776 100 00 13 088 13 5 100 00 The average economy of automobiles in the United States in 2002 was 22 0 miles per US gallon 10 7 L 100 km 26 4 mpg imp By 2010 this had increased to 23 0 miles per US gallon 10 2 L 100 km 27 6 mpg imp Average fuel economy in the United States gradually declined until 1973 when it reached a low of 13 4 miles per US gallon 17 6 L 100 km 16 1 mpg imp and gradually has increased since as a result of higher fuel cost 28 A study indicates that a 10 increase in gas prices will eventually produce a 2 04 increase in fuel economy 29 One method by car makers to increase fuel efficiency is lightweighting in which lighter weight materials are substituted in for improved engine performance and handling 30 Differences in testing standards edit Identical vehicles can have varying fuel consumption figures listed depending upon the testing methods of the jurisdiction 31 Lexus IS 250 petrol 2 5 L 4GR FSE V6 204 hp 153 kW 6 speed automatic rear wheel drive Australia L 100 km combined 9 1 urban 12 7 extra urban 7 0 21 Canada L 100 km combined 9 6 city 11 1 highway 7 8 32 European Union L 100 km combined 8 9 urban 12 5 extra urban 6 9 22 United States L 100 km combined 9 8 city 11 2 highway 8 1 23 Energy considerations editThis section needs additional citations for verification Please help improve this article by adding citations to reliable sources in this section Unsourced material may be challenged and removed Find sources Fuel economy in automobiles news newspapers books scholar JSTOR November 2023 Learn how and when to remove this message Since the total force opposing the vehicle s motion at constant speed multiplied by the distance through which the vehicle travels represents the work that the vehicle s engine must perform the study of fuel economy the amount of energy consumed per unit of distance traveled requires a detailed analysis of the forces that oppose a vehicle s motion In terms of physics Force rate at which the amount of work generated energy delivered varies with the distance traveled or F d W d s Fuel economy displaystyle F frac dW ds propto text Fuel economy nbsp Note The amount of work generated by the vehicle s power source energy delivered by the engine would be exactly proportional to the amount of fuel energy consumed by the engine if the engine s efficiency is the same regardless of power output but this is not necessarily the case due to the operating characteristics of the internal combustion engine For a vehicle whose source of power is a heat engine an engine that uses heat to perform useful work the amount of fuel energy that a vehicle consumes per unit of distance level road depends upon The thermodynamic efficiency of the heat engine Frictional losses within the drivetrain Rolling resistance within the wheels and between the road and the wheels Non motive subsystems powered by the engine such as air conditioning engine cooling and the alternator Aerodynamic drag from moving through air Energy converted by frictional brakes into waste heat or losses from regenerative braking in hybrid vehicles Fuel consumed while the engine is not providing power but still running such as while idling minus the subsystem loads 33 nbsp Energy dissipation in city and highway driving for a mid size gasoline powered car Ideally a car traveling at a constant velocity on level ground in a vacuum with frictionless wheels could travel at any speed without consuming any energy beyond what is needed to get the car up to speed Less ideally any vehicle must expend energy on overcoming road load forces which consist of aerodynamic drag tire rolling resistance and inertial energy that is lost when the vehicle is decelerated by friction brakes With ideal regenerative braking the inertial energy could be completely recovered but there are few options for reducing aerodynamic drag or rolling resistance other than optimizing the vehicle s shape and the tire design Road load energy or the energy demanded at the wheels can be calculated by evaluating the vehicle equation of motion over a specific driving cycle 34 The vehicle powertrain must then provide this minimum energy to move the vehicle and will lose a large amount of additional energy in the process of converting fuel energy into work and transmitting it to the wheels Overall the sources of energy loss in moving a vehicle may be summarized as follows Engine efficiency 20 30 which varies with engine type the mass of the automobile and its load and engine speed usually measured in RPM Aerodynamic drag force which increases roughly by the square of the car s speed but notes that drag power goes by the cube of the car s speed Rolling friction Braking although regenerative braking captures some of the energy that would otherwise be lost Losses in the transmission Manual transmissions can be up to 94 efficient whereas older automatic transmissions may be as low as 70 efficient 35 Automated manual transmissions which have the same mechanical internals as conventional manual transmissions will give the same efficiency as a pure manual gearbox plus the added bonus of intelligence selecting optimal shifting points and or automated clutch control but manual shifting as with older semi automatic transmissions Air conditioning The power required for the engine to turn the compressor decreases the fuel efficiency though only when in use This may be offset by the reduced drag of the vehicle compared with driving with the windows down The efficiency of AC systems gradually deteriorates due to dirty filters etc regular maintenance prevents this The extra mass of the air conditioning system will cause a slight increase in fuel consumption Power steering The older hydraulic power steering systems are powered by a hydraulic pump constantly engaged to the engine Power assistance required for steering is inversely proportional to the vehicle speed so the constant load on the engine from a hydraulic pump reduces fuel efficiency More modern designs improve fuel efficiency by only activating the power assistance when needed this is done by using either direct electrical power steering assistance or an electrically powered hydraulic pump Cooling The older cooling systems used a constantly engaged mechanical fan to draw air through the radiator at a rate directly related to the engine speed This constant load reduces efficiency More modern systems use electrical fans to draw additional air through the radiator when extra cooling is required Electrical systems Headlights battery charging active suspension circulating fans defrosters media systems speakers and other electronics can also significantly increase fuel consumption as the energy to power these devices causes an increased load on the alternator Since alternators are commonly only 40 60 efficient the added load from electronics on the engine can be as high as 3 horsepower 2 2 kW at any speed including idle In the FTP 75 cycle test a 200 watt load on the alternator reduces fuel efficiency by 1 7 mpg 36 Headlights for example consume 110 watts on low and up to 240 watts on high These electrical loads can cause much of the discrepancy between real world and EPA tests which only include the electrical loads required to run the engine and basic climate control Standby The energy is needed to keep the engine running while it is not providing power to the wheels i e when stopped coasting or braking Fuel efficiency decreases from electrical loads are most pronounced at lower speeds because most electrical loads are constant while engine load increases with speed So at a lower speed a higher proportion of engine horsepower is used by electrical loads Hybrid cars see the greatest effect on fuel efficiency from electrical loads because of this proportional effect Fuel economy boosting technologies edit Main article Fuel saving devices Engine specific technology edit Type Technology Explanation Inventor Notes Engine cycle Replacing petrol engines with diesel engines Reduces brake specific fuel consumption at lower RPM Herbert Akroyd Stuart Engine combustion strategies Electronic control of the cooling system Optimizes engine running temperature Stratified Charge combustion Injects fuel into cylinder just before ignition increasing compression ratio For use in petrol engines Lean burn combustion Increases air fuel ratio to reduce throttling losses Chrysler https www youtube com watch v KnNX6gtDyhg Cooled exhaust gas recirculation petrol Reduces throttling losses heat rejection chemical dissociation and specific heat ratio Cooled exhaust gas recirculation diesel Lowers peak combustion temperatures Atkinson cycle Lengthens power stroke to achieve greater thermal efficiency James Atkinson nbsp Atkinson cycle Variable valve timing and variable valve lift Alters valve lift timing and height for precise control over intake and exhaust William Howe and William Williams Robert Stephenson and Company invented the first variable timing valve Variable geometry turbocharging Optimizes airflow with adjustable vanes to regulate turbocharger s air intake and eliminate turbo lag Garrett Honeywell nbsp VNT Vanes Open Twincharging Combines a supercharger with a turbocharger to eliminate turbo lag Lancia For use in small displacement engines Gasoline direct injection GDI engines Allows for stratified fuel charge and ultra lean burn Leon Levavasseur Turbocharged Direct Injection diesel engines Combines direct injection with a turbocharger Volkswagen Common rail direct injection Increases injection pressure Robert Huber Piezoelectric diesel injectors Uses multiple injections per engine cycle for increased precision Cylinder management Shuts off individual cylinders when their power output is not needed HCCI Homogeneous Charge Compression Ignition combustion Allows leaner and higher compression burn https www youtube com watch v B8CnYljXAS0 Scuderi engine Eliminates recompression losses Carmelo J Scuderi nbsp Scuderi engine Compound engines 6 stroke engine or turbo compound engine Recovers exhaust energy Two stroke diesel engines Increases power to weight ratio Charles F Kettering High efficiency gas turbine engines Increases power to weight ratio Turbosteamer Uses heat from the engine to spin a mini turbine to generate power Raymond Freymann BMW Stirling hybrid battery vehicle Increases thermal efficiency Still largely theoretical although prototypes have been produced by Dean Kamen Time optimized piston path Captures energy from gases in the cylinders at their highest temperatures Engine internal losses Downsized engines with a supercharger or a turbocharger Reduces engine displacement while maintaining sufficient torque Saab starting with the 99 in 1978 nbsp 2014 Global Turbo Forecast Lower friction lubricants engine oil transmission fluid axle fluid Reduces energy lost to friction Lower viscosity engine oils Reduces hydrodynamic friction and energy required to circulate Variable displacement oil pump Avoids excessive flow rate at high engine speed Electrifying engine accessories water pump power steering pump and air conditioner compressor Sends more engine power to the transmission or reduces the fuel required for the same traction power Roller type cam low friction coating on piston skirt and optimizing load bearing surface e g camshaft bearing and connective rods Reduces engine frictions Engine running conditions Coolant additives Increases the thermal efficiency of the cooling system Increasing the number of gearbox ratios in manual gearboxes Lowers the engine rpm at cruise Reducing the volume of water based cooling systems Engine reaches its efficient operating temperature more quickly Start stop system Automatically shuts off engine when vehicle is stopped reducing idle time Downsized engines with an electric drive system and battery Avoids low efficiency idle and power conditions Other vehicle technologies edit Type Technology Explanation Inventor Notes Transmission losses Continuously variable transmission CVT Enables engine to run at its most efficient RPM For use in automatic gearboxes Locking torque converters in automatic transmissions Reduces slip and power losses in the converter Rolling resistance Lighter construction materials aluminum fiberglass plastic high strength steel and carbon fiber Reduces vehicle weight Increasing tire pressure Lowers tire deformation underweight Replacing tires with low rolling resistance LRR models Lowers rolling resistance 37 Series parallel hybrid Using an electric motor for the base power and an IC engine for assists and boosts when needed Decreases fuel consumption by running the petrol engine only when needed in this way also environmentally friendly TRW Energy saving Lighter materials for moving parts pistons crankshaft gears and alloy wheels Reduces the energy required to move parts Regenerative braking Captures kinetic energy while braking Louis Antoine Krieger For use in hybrid or electric vehicles Recapturing waste heat from the exhaust system Converts heat energy into electricity using thermoelectric cooling Jean Charles Athanase Peltier Regenerative shock absorbers Recaptures wasted energy in the vehicle suspension 38 Levant Power Traffic management Active highway management Matches speed limits and vehicles allowed to join motorways with traffic density to maintain traffic throughput Vehicle electronic control systems that automatically maintain distances between vehicles on motorways Reduces ripple back braking and consequent re acceleration Future technologies edit Technologies that may improve fuel efficiency but are not yet on the market include HCCI Homogeneous Charge Compression Ignition combustion Scuderi engine Compound engines Two stroke diesel engines High efficiency gas turbine engines BMW s Turbosteamer using the heat from the engine to spin a mini turbine to generate power Vehicle electronic control systems that automatically maintain distances between vehicles on motorways freeways that reduce ripple back braking and consequent re acceleration Time optimized piston path to capture energy from hot gases in the cylinders when they are at their highest temperatures citation needed sterling hybrid battery vehicle Many aftermarket consumer products exist that are purported to increase fuel economy many of these claims have been discredited In the United States the Environmental Protection Agency maintains a list of devices that have been tested by independent laboratories and makes the test results available to the public 39 Fuel economy maximizing behaviors edit Main article Fuel economy maximizing behaviors Governments various environmentalist organizations and companies like Toyota and Shell Oil Company have historically urged drivers to maintain adequate air pressure in tires and careful acceleration deceleration habits Keeping track of fuel efficiency stimulates fuel economy maximizing behavior 40 A five year partnership between Michelin and Anglian Water shows that 60 000 liters of fuel can be saved on tire pressure The Anglian Water fleet of 4 000 vans and cars are now lasting their full lifetime This shows the impact that tire pressures have on the fuel efficiency 41 Fuel economy as part of quality management regimes edit Environmental management systems EMAS as well as good fleet management includes record keeping of the fleet fuel consumption Quality management uses those figures to steer the measures acting on the fleets This is a way to check whether procurement driving and maintenance in total have contributed to changes in the fleet s overall consumption Fuel economy standards and testing procedures editGasoline new passenger car fuel efficiency Country 2004 average Requirement 2004 2005 2008 Later People s Republic of China 42 6 9 L 100 km 6 9 L 100 km 6 1 L 100 km United States 24 6 mpg 9 5 L 100 km cars and trucks 27 mpg 8 7 L 100 km cars only 35 mpg 6 7 L 100 km Model Year 2020 cars amp light trucks European Union 4 1 L 100 km 2020 NEDC Japan 14 6 7 L 100 km CAFE eq 2010 Australia 14 8 08 L 100 km CAFE eq 2002 none none as of March 2019 43 highway combined Australia edit From October 2008 all new cars had to be sold with a sticker on the windscreen showing the fuel consumption and the CO2 emissions 44 Fuel consumption figures are expressed as urban extra urban and combined measured according to ECE Regulations 83 and 101 which are the based on the European driving cycle previously only the combined number was given Australia also uses a star rating system from one to five stars that combines greenhouse gases with pollution rating each from 0 to 10 with ten being best To get 5 stars a combined score of 16 or better is needed so a car with a 10 for economy greenhouse and a 6 for emission or 6 for economy and 10 for emission or anything in between would get the highest 5 star rating 45 The lowest rated car is the Ssangyong Korrando with automatic transmission with one star while the highest rated was the Toyota Prius hybrid The Fiat 500 Fiat Punto and Fiat Ritmo as well as the Citroen C3 also received 5 stars 46 The greenhouse rating depends on the fuel economy and the type of fuel used A greenhouse rating of 10 requires 60 or less grams of CO2 per km while a rating of zero is more than 440 g km CO2 The highest greenhouse rating of any 2009 car listed is the Toyota Prius with 106 g km CO2 and 4 4 L 100 km 64 mpg imp 53 mpg US Several other cars also received the same rating of 8 5 for greenhouse The lowest rated was the Ferrari 575 at 499 g km CO2 and 21 8 L 100 km 13 0 mpg imp 10 8 mpg US The Bentley also received a zero rating at 465 g km CO2 The best fuel economy of any year is the 2004 2005 Honda Insight at 3 4 L 100 km 83 mpg imp 69 mpg US Canada edit Vehicle manufacturers follow a controlled laboratory testing procedure to generate the fuel consumption data that they submit to the Government of Canada This controlled method of fuel consumption testing including the use of standardized fuels test cycles and calculations is used instead of on road driving to ensure that all vehicles are tested under identical conditions and that the results are consistent and repeatable Selected test vehicles are run in for about 6 000 km before testing The vehicle is then mounted on a chassis dynamometer programmed to take into account the aerodynamic efficiency weight and rolling resistance of the vehicle A trained driver runs the vehicle through standardized driving cycles that simulate trips in the city and on the highway Fuel consumption ratings are derived from the emissions generated during the driving cycles 47 THE 5 CYCLE TEST The city test simulates urban driving in stop and go traffic with an average speed of 34 km h and a top speed of 90 km h The test runs for approximately 31 minutes and includes 23 stops The test begins from a cold engine start which is similar to starting a vehicle after it has been parked overnight during the summer The final phase of the test repeats the first eight minutes of the cycle but with a hot engine start This simulates restarting a vehicle after it has been warmed up driven and then stopped for a short time Over five minutes of test time are spent idling to represent waiting at traffic lights The ambient temperature of the test cell starts at 20 C and ends at 30 C The highway test simulates a mixture of open highway and rural road driving with an average speed of 78 km h and a top speed of 97 km h The test runs for approximately 13 minutes and does not include any stops The test begins from a hot engine start The ambient temperature of the test cell starts at 20 C and ends at 30 C In the cold temperature operation test the same driving cycle is used as in the standard city test except that the ambient temperature of the test cell is set to 7 C In the air conditioning test the ambient temperature of the test cell is raised to 35 C The vehicle s climate control system is then used to lower the internal cabin temperature Starting with a warm engine the test averages 35 km h and reaches a maximum speed of 88 km h Five stops are included with idling occurring 19 of the time The high speed quick acceleration test averages 78 km h and reaches a top speed of 129 km h Four stops are included and brisk acceleration maximizes at a rate of 13 6 km h per second The engine begins warm and air conditioning is not used The ambient temperature of the test cell is constantly 25 C Tests 1 3 4 and 5 are averaged to create the city driving fuel consumption rate Tests 2 4 and 5 are averaged to create the highway driving fuel consumption rate 47 Europe edit nbsp Irish fuel economy label Main article New European Driving Cycle This section s factual accuracy may be compromised due to out of date information The reason given is Worldwide harmonized Light vehicles Test Procedure WLTP replaced NEDC for vehicles certified after September 2018 Please help update this article to reflect recent events or newly available information September 2018 In the European Union passenger vehicles are commonly tested using two drive cycles and corresponding fuel economies are reported as urban and extra urban in liters per 100 km and in the UK in miles per imperial gallon The urban economy is measured using the test cycle known as ECE 15 first introduced in 1970 by EC Directive 70 220 EWG and finalized by EEC Directive 90 C81 01 in 1999 It simulates a 4 052 m 2 518 mile urban trip at an average speed of 18 7 km h 11 6 mph and at a maximum speed of 50 km h 31 mph The extra urban driving cycle or EUDC lasts 400 seconds 6 minutes 40 seconds at an average speed 62 6 km h 39 mph and a top speed of 120 km h 74 6 mph 48 EU fuel consumption numbers are often considerably lower than corresponding US EPA test results for the same vehicle For example the 2011 Honda CR Z with a six speed manual transmission is rated 6 1 4 4 L 100 km in Europe 49 and 7 6 6 4 L 100 km 31 37 mpg in the United States 50 In the European Union advertising has to show carbon dioxide CO2 emission and fuel consumption data in a clear way as described in the UK Statutory Instrument 2004 No 1661 51 Since September 2005 a color coded Green Rating sticker has been available in the UK which rates fuel economy by CO2 emissions A lt 100 g km B 100 120 C 121 150 D 151 165 E 166 185 F 186 225 and G 226 Depending on the type of fuel used for gasoline A corresponds to about 4 1 L 100 km 69 mpg imp 57 mpg US and G about 9 5 L 100 km 30 mpg imp 25 mpg US 52 Ireland has a very similar label but the ranges are slightly different with A lt 120 g km B 121 140 C 141 155 D 156 170 E 171 190 F 191 225 and G 226 53 From 2020 EU requires manufacturers to average 95 g km CO2 emission or less or pay an excess emissions premium 54 In the UK the ASA Advertising standards agency have claimed that fuel consumption figures are misleading Often the case with European vehicles as the MPG miles per gallon figures that can be advertised are often not the same as real world driving The ASA have said that car manufacturers can use cheats to prepare their vehicles for their compulsory fuel efficiency and emissions tests in a way set out to make themselves look as clean as possible This practice is common in gasoline and diesel vehicle tests but hybrid and electric vehicles are not immune as manufacturers apply these techniques to fuel efficiency Car experts who also assert that the official MPG figures given by manufacturers do not represent the true MPG values from real world driving 55 Websites have been set up to show the real world MPG figures based on crowd sourced data from real users vs the official MPG figures 56 The major loopholes in the current EU tests allow car manufacturers a number of cheats to improve results Car manufacturers can Disconnect the alternator thus no energy is used to recharge the battery Use special lubricants that are not used in production cars in order to reduce friction Turn off all electrical gadgets i e Air Con Radio Adjust brakes or even disconnect them to reduce friction Tape up cracks between body panels and windows to reduce air resistance Remove Wing mirrors 57 According to the results of a 2014 study by the International Council on Clean Transportation ICCT the gap between official and real world fuel economy figures in Europe has risen to about 38 in 2013 from 10 in 2001 The analysis found that for private cars the difference between on road and official CO2 values rose from around 8 in 2001 to 31 in 2013 and 45 for company cars in 2013 The report is based on data from more than half a million private and company vehicles across Europe The analysis was prepared by the ICCT together with the Netherlands Organization for Applied Scientific Research TNO and the German Institut fur Energie und Umweltforschung Heidelberg IFEU 58 In 2018 update of the ICCT data the difference between the official and real figures was again 38 59 Japan edit The evaluation criteria used in Japan reflects driving conditions commonly found as the typical Japanese driver does not drive as fast as other regions internationally Speed limits in Japan 10 15 mode edit The 10 15 mode driving cycle test is the official fuel economy and emission certification test for new light duty vehicles in Japan Fuel economy is expressed in km L kilometers per liter and emissions are expressed in g km The test is carried out on a dynamometer and consist of 25 tests which cover idling acceleration steady running and deceleration and simulate typical Japanese urban and or expressway driving conditions The running pattern begins with a warm start lasts for 660 seconds 11 minutes and runs at speeds up to 70 km h 43 5 mph 60 61 The distance of the cycle is 6 34 km 3 9 mi average speed of 25 6 km h 15 9 mph and duration 892 seconds 14 9 minutes including the initial 15 mode segment 61 JC08 edit A new more demanding test called the JC08 was established in December 2006 for Japan s new standard that goes into effect in 2015 but it is already being used by several car manufacturers for new cars The JC08 test is significantly longer and more rigorous than the 10 15 mode test The running pattern with JC08 stretches out to 1200 seconds 20 minutes and there are both cold and warm start measurements and top speed is 82 km h 51 0 mph The economy ratings of the JC08 are lower than the 10 15 mode cycle but they are expected to be more real world 60 The Toyota Prius became the first car to meet Japan s new 2015 Fuel Economy Standards measured under the JC08 test 62 New Zealand edit Starting on 7 April 2008 all cars of up to 3 5 tonnes GVW sold other than private sale need to have a fuel economy sticker applied if available that shows the rating from one half star to six stars with the most economic cars having the most stars and the more fuel hungry cars the least along with the fuel economy in L 100 km and the estimated annual fuel cost for driving 14 000 km at present fuel prices The stickers must also appear on vehicles to be leased for more than 4 months All new cars currently rated range from 6 9 L 100 km 41 mpg imp 34 mpg US to 3 8 L 100 km 74 mpg imp 62 mpg US and received respectively from 4 5 to 5 5 stars 63 Saudi Arabia edit The Kingdom of Saudi Arabia announced new light duty vehicle fuel economy standards in November 2014 which became effective 1 January 2016 and will be fully phased in by 1 January 2018 Saudi Standards regulation SASO 2864 A review of the targets will be carried by December 2018 at which time targets for 2021 2025 will be set United States edit nbsp Motor vehicle fuel economy from 1949 to 2021 US Energy Tax Act edit Main article Energy Tax Act The Energy Tax Act of 1978 64 in the US established a gas guzzler tax on the sale of new model year vehicles whose fuel economy fails to meet certain statutory levels The tax applies only to cars not trucks and is collected by the IRS Its purpose is to discourage the production and purchase of fuel inefficient vehicles The tax was phased in over ten years with rates increasing over time It applies only to manufacturers and importers of vehicles although presumably some or all of the tax is passed along to automobile consumers in the form of higher prices Only new vehicles are subject to the tax so no tax is imposed on used car sales The tax is graduated to apply a higher tax rate for less fuel efficient vehicles To determine the tax rate manufacturers test all the vehicles at their laboratories for fuel economy The US Environmental Protection Agency confirms a portion of those tests at an EPA lab In some cases this tax may apply only to certain variants of a given model for example the 2004 2006 Pontiac GTO captive import version of the Holden Monaro did incur the tax when ordered with the four speed automatic transmission but did not incur the tax when ordered with the six speed manual transmission 65 EPA testing procedure through 2007 edit nbsp The city or Urban Dynamometer Driving Schedule UDDS used in the EPA Federal Test Procedure nbsp The Highway Fuel Economy Driving Cycle HWFET used in the EPA Federal Test Procedure Two separate fuel economy tests simulate city driving and highway driving the city driving program or Urban Dynamometer Driving Schedule or UDDS or FTP 72 is defined in 40 CFR 86 I and consists of starting with a cold engine and making 23 stops over a period of 31 minutes for an average speed of 20 mph 32 km h and with a top speed of 56 mph 90 km h The highway program or Highway Fuel Economy Driving Schedule HWFET is defined in 40 CFR 600 I and uses a warmed up engine and makes no stops averaging 48 mph 77 km h with a top speed of 60 mph 97 km h over a 10 mile 16 km distance A weighted average of city 55 and highway 45 fuel economies is used to determine the combined rating and guzzler tax 66 67 68 This rating is what is also used for light duty vehicle corporate average fuel economy regulations The procedure has been updated to FTP 75 adding a hot start cycle which repeats the cold start cycle after a 10 minute pause Because EPA figures had almost always indicated better efficiency than real world fuel efficiency the EPA has modified the method starting with 2008 Updated estimates are available for vehicles back to the 1985 model year 66 69 EPA testing procedure 2008 and beyond edit nbsp 2008 Monroney sticker highlights fuel economy US EPA altered the testing procedure effective MY2008 which adds three new Supplemental Federal Test Procedure SFTP tests to include the influence of higher driving speed harder acceleration colder temperature and air conditioning use 70 SFTP US06 is a high speed quick acceleration loop that lasts 10 minutes covers 8 miles 13 km averages 48 mph 77 km h and reaches a top speed of 80 mph 130 km h Four stops are included and brisk acceleration maximizes at a rate of 8 46 mph 13 62 km h per second The engine begins warm and air conditioning is not used Ambient temperature varies between 68 F 20 C to 86 F 30 C SFTO SC03 is the air conditioning test which raises ambient temperatures to 95 F 35 C and puts the vehicle s climate control system to use Lasting 9 9 minutes the 3 6 mile 5 8 km loop averages 22 mph 35 km h and maximizes at a rate of 54 8 mph 88 2 km h Five stops are included idling occurs 19 percent of the time and acceleration of 5 1 mph per second is achieved Engine temperatures begin warm Lastly a cold temperature cycle uses the same parameters as the current city loop except that ambient temperature is set to 20 F 7 C EPA tests for fuel economy do not include electrical load tests beyond climate control which may account for some of the discrepancy between EPA and real world fuel efficiency A 200 W electrical load can produce a 0 4 km L 0 94 mpg reduction in efficiency on the FTP 75 cycle test 36 Beginning with model year 2017 the calculation method changed to improve the accuracy of the estimated 5 cycle city and highway fuel economy values derived from just the FTP and HFET tests with lower uncertainty for fuel efficient vehicles 71 Electric vehicles and hybrids edit nbsp 2010 Monroney sticker for a plug in hybrid showing fuel economy in all electric mode and gasoline only mode Following the efficiency claims made for vehicles such as Chevrolet Volt and Nissan Leaf the National Renewable Energy Laboratory recommended to use EPA s new vehicle fuel efficiency formula that gives different values depending on fuel used 72 In November 2010 the EPA introduced the first fuel economy ratings in the Monroney stickers for plug in electric vehicles For the fuel economy label of the Chevy Volt plug in hybrid EPA rated the car separately for all electric mode expressed in miles per gallon gasoline equivalent MPG e and for gasoline only mode expressed in conventional miles per gallon EPA also estimated an overall combined city highway gas electricity fuel economy rating expressed in miles per gallon gasoline equivalent MPG e The label also includes a table showing fuel economy and electricity consumed for five different scenarios 30 miles 48 km 45 miles 72 km 60 miles 97 km and 75 miles 121 km driven between a full charge and a never charge scenario This information was included to make the consumers aware of the variability of the fuel economy outcome depending on miles driven between charges Also the fuel economy for a gasoline only scenario never charge was included For electric only mode the energy consumption estimated in kWh per 100 miles 160 km is also shown 73 74 nbsp 2010 Monroney label showing the EPA s combined city highway fuel economy equivalent for an all electric car in this case a 2010 Nissan Leaf For the fuel economy label of the Nissan Leaf electric car EPA rated the combined fuel economy in terms of miles per gallon gasoline equivalent with a separate rating for city and highway driving This fuel economy equivalence is based on the energy consumption estimated in kWh per 100 miles and also shown in the Monroney label 75 In May 2011 the National Highway Traffic Safety Administration NHTSA and EPA issued a joint final rule establishing new requirements for a fuel economy and environment label that is mandatory for all new passenger cars and trucks starting with model year 2013 and voluntary for 2012 models The ruling includes new labels for alternative fuel and alternative propulsion vehicles available in the US market such as plug in hybrids electric vehicles flexible fuel vehicles hydrogen fuel cell vehicle and natural gas vehicles 76 77 The common fuel economy metric adopted to allow the comparison of alternative fuel and advanced technology vehicles with conventional internal combustion engine vehicles is miles per gallon of gasoline equivalent MPGe A gallon of gasoline equivalent means the number of kilowatt hours of electricity cubic feet of compressed natural gas CNG or kilograms of hydrogen that is equal to the energy in a gallon of gasoline 76 The new labels also include for the first time an estimate of how much fuel or electricity it takes to drive 100 miles 160 km providing US consumers with fuel consumption per distance traveled the metric commonly used in many other countries EPA explained that the objective is to avoid the traditional miles per gallon metric that can be potentially misleading when consumers compare fuel economy improvements and known as the MPG illusion 78 this illusion arises because the reciprocal i e non linear relationship between cost equivalently volume of fuel consumed per unit distance driven and MPG value means that differences in MPG values are not directly meaningful only ratios are in mathematical terms the reciprocal function does not commute with addition and subtraction in general a difference in reciprocal values is not equal to the reciprocal of their difference It has been claimed that many consumers are unaware of this and therefore compare MPG values by subtracting them which can give a misleading picture of relative differences in fuel economy between different pairs of vehicles for instance an increase from 10 to 20 MPG corresponds to a 100 improvement in fuel economy whereas an increase from 50 to 60 MPG is only a 20 improvement although in both cases the difference is 10 MPG 79 The EPA explained that the new gallons per 100 miles metric provides a more accurate measure of fuel efficiency 76 80 notably it is equivalent to the normal metric measurement of fuel economy liters per 100 kilometers L 100 km CAFE standards edit nbsp Curve of average car mileage for model years between 1978 and 2014Main article Corporate Average Fuel Economy The Corporate Average Fuel Economy CAFE regulations in the United States first enacted by Congress in 1975 81 are federal regulations intended to improve the average fuel economy of cars and light trucks trucks vans and sport utility vehicles sold in the US in the wake of the 1973 Arab Oil Embargo Historically it is the sales weighted average fuel economy of a manufacturer s fleet of current model year passenger cars or light trucks manufactured for sale in the United States Under Truck CAFE standards 2008 2011 this changes to a footprint model where larger trucks are allowed to consume more fuel The standards were limited to vehicles under a certain weight but those weight classes were expanded in 2011 Federal and state regulations edit The Clean Air Act of 1970 prohibited states from establishing their own air pollution standards However the legislation authorized the EPA to grant a waiver to California allowing the state to set higher standards 82 The law provides a piggybacking provision that allows other states to adopt vehicle emission limits that are the same as California s 83 California s waivers were routinely granted until 2007 when the George W Bush administration rejected the state s bid to adopt global warming pollution limits for cars and light trucks 84 California and 15 other states that were trying to put in place the same emissions standards sued in response 85 The case was tied up in court until the Obama administration reversed the policy in 2009 by granting the waiver 86 In August 2012 President Obama announced new standards for American made automobiles of an average of 54 5 miles per gallon by the year 2025 87 88 In April 2018 EPA Administrator Scott Pruitt announced that the Trump administration planned to roll back the 2012 federal standards and would also seek to curb California s authority to set its own standards 82 Although the Trump administration was reportedly considering a compromise to allow state and national standards to stay in place 89 on 21 February 2019 the White House declared that it had abandoned these negotiations 90 A government report subsequently found that in 2019 new light duty vehicle fuel economy fell 0 2 miles per gallon to 24 9 miles per gallon and pollution increased 3 grams per mile traveled to 356 grams per mile A decrease in fuel economy and an increase in pollution had not occurred for the previous five years 91 The Obama era rule was officially rolled back on 31 March 2020 during the Trump administration 92 but the rollback was reversed on 20 December 2021 during the Biden administration 93 Fuel economy of trucks editTrucks are usually bought as an investment good They are meant to earn money As the Diesel fuel burnt in heavy trucks accounts for around 30 94 of the total costs for a freight forwarding company there is always a lot of interest in both the haulage industry and the truck builder industry to strive for best fuel economy For truck buyers the fuel economy measured by standard procedures is only a first guideline Professional trucking companies measure the fuel economy of their trucks and truck fleets in real usage Fuel economy of trucks in real usage is determined by four important factors 94 The truck technology that is constantly improved by the various OEMs The driver s driving style contributes a lot to the real fuel economy different from the test cycles where a standard driving style is used The maintenance condition of the vehicle influences the fuel efficiency again different from standardized procedures where the trucks are always presented in flawless condition Last but not least the usage of the vehicle influences the fuel consumption Hilly roads and heavy loads will increase the fuel consumption of a vehicle Effect on pollution editFurther information Gas guzzler and Vehicle Efficiency Initiative Fuel efficiency directly affects emissions causing pollution by affecting the amount of fuel used However it also depends on the fuel source used to drive the vehicle concerned Cars for example can run on a number of fuel types other than gasoline such as natural gas LPG or biofuel or electricity which creates various quantities of atmospheric pollution A kilogram of carbon whether contained in petrol diesel kerosene or any other hydrocarbon fuel in a vehicle leads to approximately 3 6 kg of CO2 emissions 95 Due to the carbon content of gasoline its combustion emits 2 3 kg L 19 4 lb US gal of CO2 since diesel fuel is more energy dense per unit volume diesel emits 2 6 kg L 22 2 lb US gal 95 This figure is only the CO2 emissions of the final fuel product and does not include additional CO2 emissions created during the drilling pumping transportation and refining steps required to produce the fuel Additional measures to reduce overall emission includes improvements to the efficiency of air conditioners lights and tires Unit conversions editUS Gallons 1 mpg 0 425 km L 235 2 mpg L 100 km 1 mpg 1 201 mpg imp Imperial gallons 1 mpg 0 354 km L 282 mpg L 100 km 1 mpg 0 833 mpg US Conversion from mpg edit mpg imp mpg US km L L 100 km 5 4 2 1 8 56 5 10 8 3 3 5 28 2 15 12 5 5 3 18 8 20 16 7 7 1 14 1 25 20 8 8 9 11 3 30 25 0 10 6 9 4 35 29 1 12 4 8 1 40 33 3 14 2 7 1 45 37 5 15 9 6 3 50 41 6 17 7 5 6 55 45 8 19 5 5 1 60 50 0 21 2 4 7 65 54 1 23 0 4 3 70 58 3 24 8 4 0 75 62 5 26 6 3 8 80 66 6 28 3 3 5 85 70 8 30 1 3 3 90 74 9 31 9 3 1 95 79 1 33 6 3 0 100 83 3 35 4 2 8 mpg US mpg imp km L L 100 km 5 6 0 2 1 47 0 10 12 0 4 3 23 5 15 18 0 6 4 15 7 20 24 0 8 5 11 8 25 30 0 10 6 9 4 30 36 0 12 8 7 8 35 42 0 14 9 6 7 40 48 0 17 0 5 9 45 54 0 19 1 5 2 50 60 0 21 3 4 7 55 66 1 23 4 4 3 60 72 1 25 5 3 9 65 78 1 27 6 3 6 70 84 1 29 8 3 4 75 90 1 31 9 3 1 80 96 1 34 0 2 9 85 102 1 36 1 2 8 90 108 1 38 3 2 6 95 114 1 40 4 2 5 100 120 1 42 5 2 4 Conversion from km L and L 100 km edit L 100 km km L mpg US mpg imp 1 100 0 235 2 282 5 2 50 0 117 6 141 2 3 33 3 78 4 94 2 4 25 0 58 8 70 6 5 20 0 47 0 56 5 6 16 7 39 2 47 1 7 14 3 33 6 40 4 8 12 5 29 4 35 3 9 11 1 26 1 31 4 10 10 0 23 5 28 2 15 6 7 15 7 18 8 20 5 0 11 8 14 1 25 4 0 9 4 11 3 30 3 3 7 8 9 4 35 2 9 6 7 8 1 40 2 5 5 9 7 1 45 2 2 5 2 6 3 50 2 0 4 7 5 6 55 1 8 4 3 5 1 60 1 7 3 9 4 7 km L L 100 km mpg US mpg imp 5 20 0 11 8 14 1 10 10 0 23 5 28 2 15 6 7 35 3 42 4 20 5 0 47 0 56 5 25 4 0 58 8 70 6 30 3 3 70 6 84 7 35 2 9 82 3 98 9 40 2 5 94 1 113 0 45 2 2 105 8 127 1 50 2 0 117 6 141 2 55 1 8 129 4 155 4 60 1 7 141 1 169 5 65 1 5 152 9 183 6 70 1 4 164 7 197 7 75 1 3 176 4 211 9 80 1 3 188 2 226 0 85 1 2 199 9 240 1 90 1 1 211 7 254 2 95 1 1 223 5 268 4 100 1 0 235 2 282 5See also editAutomobile costs ACEA agreement Battery electric vehicle Car speed and energy consumption Car tuning Emission standard Energy conservation Energy efficient driving FF layout Fuel efficiency in transportation Fuel saving devices Gasoline gallon equivalent Motorized quadricycle vehicles with low power engines low top speed Miles per gallon gasoline equivalent Passenger miles per gallon The Very Light Car Vehicle Efficiency Initiative Vehicle metrics Green vehicle Low carbon economy Low rolling resistance tires Microcar Plug in hybridAnnotations edit Specifically the production weighted harmonic mean The 2 2 drop figure was calculated by finding daily consumption to be 9 299 684 barrels of petroleum Obtain 1973 s petroleum consumption from transportation sector at 2 1e from the Energy Consumption by Sector section then convert to barrels using A1 in the Thermal Conversion Factors section assume conventional motor gasoline since ethanol based or purportedly smog reducing gas was not common in 1973 17 References edit Page Walter Hines Page Arthur Wilson 1916 Man and His Machines The World s Work Vol XXXIII Garden City New York Doubleday Page amp Co What counts as good MPG nowadays 21 December 2016 Fuel Consumption Ratings Government of Canada January 2011 Retrieved 8 June 2011 FAQs Transport Canada Archived from the original on 3 September 2012 Retrieved 6 November 2012 The Passenger Car Fuel Consumption and CO2 Emissions Information Regulations 2001 2001 Retrieved 11 November 2014 The New Fuel Economy Label at FuelEconomy gov Highlights of the Automotive Trends Report EPA gov U S Environmental Protection Agency EPA 12 December 2022 Archived from the original on 2 September 2023 Cazzola Pierpaolo Paoli Leonardo Teter Jacob November 2023 Trends in the Global Vehicle Fleet 2023 Managing the SUV Shift and the EV Transition PDF Global Fuel Economy Initiative GFEI p 3 doi 10 7922 G2HM56SV Archived PDF from the original on 26 November 2023 Paul R Portney Ian W H Parry Howard K Gruenspecht Winston Harrington November 2003 The Economics of Fuel Economy Standards PDF Resources for the Future Archived from the original PDF on 1 December 2007 Retrieved 4 January 2008 a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Highlights of the Automotive Trends Report US EPA November 2021 Retrieved 30 November 2021 2019 Best and Worst Fuel Economy Vehicles US EPA Retrieved 23 June 2019 Reducing CO2 emissions from passenger cars Policies Climate Action European Commission Ec europa eu 9 December 2010 Retrieved 21 September 2011 Myth Cars are becoming more fuel efficient Ptua org au Retrieved 21 September 2011 a b c Comparison of Passenger Vehicle Fuel Economy and GHG Emission Standards Around the World at Pew Center on Global Climate Change Archived 13 April 2008 at the Wayback Machine PDF Retrieved 21 September 2011 a b c Steady Speed Fuel Economy Archived 24 September 2012 at the Wayback Machine The two earlier studies by the Federal Highway Administration FHWA indicate maximum fuel efficiency was achieved at speeds of 35 to 40 mph 55 to 65 km h The recent FHWA study indicates greater fuel efficiency at higher speeds Cowan Edward 27 November 1973 Politics and Energy Nixon s Silence on Rationing Reflects Hope That Austerity Can Be Avoided The New York Times p 30 Staff 28 June 2008 Annual Energy Review PDF 2007 ed Washington DC Energy Information Administration Archived from the original PDF on 26 September 2018 55 Mile per hour Speed Limit Approved by House United Press International 4 December 1973 p 30 Retrieved 22 July 2008 subscription required Special Report 254 Managing Speed PDF Transportation Research Board 189 Retrieved 17 September 2014 Bloomquist 1984 estimated that the 1974 National Maximum Speed Limit NMSL reduced fuel consumption by 0 2 to 1 0 percent a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Highway Statistics 1973 Table VM 2 VEHICLE MILES BY STATE AND HIGHWAY SYSTEM 1973 PDF Federal Highway Administration 76 Archived from the original PDF on 4 March 2013 Retrieved 17 September 2014 a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help a b Lexus IS250 2 5L 6cyl Auto 6 speed Sedan 5 seats 2WD Archived from the original on 4 August 2012 a b IS 250 Kraftstoffverbrauch kombiniert 8 9 L 100 km innerorts 12 5 L ausserorts 6 9 L bei CO2 Emissionen von 209 g km nach dem vorgeschriebenen EU Messverfahren LEXUS Lexus IS Sportlimousine Cabriolet Cabrio Kabrio Coupe Coupe Hochleistung IS F High Performance Fahrzeug IS F Archived from the original on 2 April 2010 Retrieved 22 April 2010 a b 2009 Lexus IS 250 6 cyl 2 5 L Automatic S6 Premium http www fueleconomy gov feg findacar htm Gas prices too high Try Europe Christian Science Monitor 26 August 2005 Archived from the original on 18 September 2012 U S stuck in reverse on fuel economy NBC News 28 February 2007 VW Lupo Rough road to fuel economy Heavy Vehicles and Characteristics Archived 2012 07 23 at the Wayback Machine Table 5 4 Light Vehicles and Characteristics Archived 2012 09 15 at the Wayback Machine Table 4 1 How Do Gasoline Prices Affect Fleet Fuel Economy Archived 2012 10 21 at the Wayback Machine Dee Ann Durbin of the Associated Press June 17 2014 Mercury News Auto industry gets serious about lighter materials Archived 2015 04 15 at the Wayback 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Guide U S Environmental Protection Agency and U S Department of Energy April 2014 Fuel Efficiency in Electric Hybrid and Petrol Cars Model Year 2019 Retrieved from https en wikipedia org w index php title Fuel economy in automobiles amp oldid 1220365416, wikipedia, wiki, book, books, library,

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