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Frequently Asked Questions

Fuel Economy Estimates

How are fuel economy ratings determined?

EPA estimates are based on laboratory tests conducted by manufacturers according to federal regulations. EPA re-tests about 10% of vehicle models to confirm manufacturer's results. For more detailed information, visit our page on How Vehicles Are Tested.

Why does my fuel economy differ from EPA estimates?

No test can accurately predict fuel economy for all drivers and all driving conditions. Driver behavior, driving conditions, vehicle maintenance, fuel characteristics, weather, and other factors can all affect fuel economy significantly as explained here.

What should I do if my fuel economy is excessively low?

If your fuel economy is excessively low, your vehicle may need to be serviced or repaired. You may want to contact your dealer or a reputable repair facility to check your vehicle. The following are some of the diagnostic checks a mechanic will typically conduct for poor fuel economy:

  • Perform "On-Board Diagnostic System Check" for diagnostic trouble codes (sensors or actuators which may be malfunctioning)
  • Check for dragging brakes
  • Check transmission shift patterns for slipping, use of all gears, lock-up operation
  • Check ignition timing
  • Check owner's driving habits including A/C usage, hard accelerations, carrying heavy loads
  • Check emission control system
  • Check vacuum hoses for leaks, kinks, proper routing
  • Check tire pressure
  • Check fuel type, quality, and alcohol content
  • Check fuel pressure and fuel system for leaks
  • Check air cleaner element
  • Check coolant level
  • Check ignition system for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits, cracking or improperly connected ignition wires
  • Check for proper calibration of speedometer
  • In extreme cases, there may be engine problems such as poor compression or faulty fuel injectors

Why don't you have ratings for large vans, pickup trucks and SUVs?

Vans, pickup trucks, and sport utility vehicles (SUVs) weighing more than 8,500 pounds gross vehicle weight are classified as heavy-duty vehicles. Fuel economy regulations do not apply to these vehicles, so they are not tested. Additional information is available at Which Vehicles Are Tested?

How are vehicle size classes defined?

The size class for cars is based on interior passenger and cargo volumes as described below. The size class for trucks is defined by the gross vehicle weight rating (GVWR), which is the weight of the vehicle and its carrying capacity. Fuel economy regulations do not apply to heavy-duty vehicles, so they are not tested. See Which Vehicles Are Tested for more information on these vehicles.

Vehicle Size Classes Used in the Fuel Economy Guide
CARS
Class Passenger & Cargo Volume (Cu. Ft.)
Two-Seaters Any (cars designed to seat only two adults)
Sedans
  Minicompact Less than 85
  Subcompact 85 to 99
  Compact 100 to 109
  Mid-Size 110 to 119
  Large 120 or more
Station Wagons
  Small Less than 130
  Mid-Size 130 to 159
  Large 160 or more
TRUCKS
Class Gross Vehicle Weight Rating (GVWR)*
Pickup Trucks  Through 2007 Beginning 2008
  Small Less than 4,500 lbs. Less than 6,000 lbs.
  Standard 4,500 to 8,500 lbs. 6,000 to 8,500 lbs.
Vans Through 2010 Beginning 2011
  Passenger Less than 8,500 lbs. Less than 10,000 lbs.
  Cargo Less than 8,500 lbs.
Minivans Less than 8,500 lbs.
Sport Utility Vehicles
  Through 2010 2011–2012
  All Less than 8,500 lbs. Less than 10,000 lbs.
  Beginning 2013
  Small Less than 6,000 lbs.
  Standard 6,000 to 9,999 lbs.
Special Purpose Vehicles Through 2010 Beginning 2011
Less than 8,500 lbs. Less than 8,500 lbs.
or less than 10,000,
depending on configuration

*Gross Vehicle Weight Rating (GVWR) is calculated as truck weight plus carrying capacity.

Where can I find more information about Corporate Average Fuel Economy (CAFE)?

First enacted by Congress in 1975, the purpose of CAFE is to reduce energy consumption by increasing the fuel economy of cars and light trucks. Information on CAFE is available from the National Highway Traffic Safety Administration.

Do EPA fuel economy estimates account for the use of ethanol blends that are common today?

No. The EPA fuel economy tests use 100 percent gasoline, and no adjustments are made to account for ethanol. Most conventional vehicles using E10 (10 percent ethanol) will experience a 3 to 4 percent reduction in fuel economy.

Why don't EPA fuel economy tests use ethanol-blended gasoline now that most gasoline contains ethanol?

EPA fuel economy tests are conducted according to Federal testing regulations which require 100 percent gasoline. These regulations could be changed, but changing them would be somewhat problematic. While it is common for gasoline pumps to allow for up to 10 percent ethanol, the actual amount of ethanol blended into the gasoline varies greatly, and fuel blending requirements vary by state. Changing the test methods would also make it difficult to compare vehicles tested with ethanol blends with those tested with straight gasoline. So, without a national standard for blended regular gasoline and a Federal mandate to change the test fuel used, the EPA will not change the test fuel.

What is the average fuel economy of vehicles in the U.S.?

Average fuel economy for 2013 model year vehicles is 27.4 mpg for cars, 19.7 mpg for trucks, and 24 mpg for light-duty cars and trucks combined. Today's passenger vehicles are nearly twice as efficient, on average, as they were in 1975.

Data Source: EPA. 2013. Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends: 1975 Through 2013 (EPA-420-R-13-011).Adobe Acrobat Icon

Fuels and Fuel Prices

What does gasoline cost?

Links to information on the cost of gasoline in the United States can be found in the Gasoline Prices section.

Should I use regular or premium gasoline?

The Federal Trade Commission's page, Facts for Consumers, answers this and other questions about octane ratings, fuel grades, and choosing the right fuel for your vehicle.

Where does gasoline from my local station come from?

The Department of Energy does not collect data on the source of gasoline sold at gas stations. However, they do provide a Primer on Gasoline Sources and Markets that explains why this is difficult to determine.

Where can I buy E85, biodiesel, or other alternative fuels?

The Alternative Fuels Data Center's Alternative Fueling Station Locator can help you find alternative fueling stations in your area.

Tax Incentives and Disincentives

What tax incentives are available for alternative fuel and hybrid vehicles?

Fueleconomy.gov's Tax Information Center provides tax incentive information for

What is the Gas Guzzler Tax?

Gas Guzzler Tax
Unadjusted MPG
(city/highway combined)
Tax
At least 22.5 $0
At least 21.5, but less than 22.5 $1,000
At least 20.5, but less than 21.5 $1,300
At least 19.5, but less than 20.5 $1,700
At least 18.5, but less than 19.5 $2,100
At least 17.5, but less than 18.5 $2,600
At least 16.5, but less than 17.5 $3,000
At least 15.5, but less than 16.5 $3,700
At least 14.5, but less than 15.5 $4,500
At least 13.5, but less than 14.5 $5,400
At least 12.5, but less than 13.5 $6,400
Less than 12.5 $7,700

The Energy Tax Act of 1978 established a Gas Guzzler Tax on the sale of new cars with particularly poor fuel economy to discourage the production of such vehicles—trucks are exempt. It is collected directly from the manufacturer rather than the buyer. The amount paid by the manufacturer is disclosed on the automobile's fuel economy label (the window sticker on new cars).

The fuel economy figures used to determine the Gas Guzzler Tax are different from the fuel economy values provided on this web site and in the Fuel Economy Guide. The tax does not depend on the actual on-the-road fuel economy, which may be more or less than the EPA published value for some drivers.

Environment

How are total annual greenhouse gas emissions estimated?

The greenhouse gas estimates presented here are full fuel-cycle estimates, combining the three major greenhouse gases emitted by motor vehicles:

  • Carbon dioxide (CO2)
  • Nitrous oxide (NOx)
  • Methane (CH4)

Full fuel-cycle estimates include all steps in the use of a fuel, from production and refining to distribution and final use. This gives a more complete picture of the climate change impacts of using a particular fuel.

Some greenhouse gases have greater impacts on climate than others. Scientists have developed relative global warming potential numbers for each gas that gives its impact on global climate relative to that of carbon dioxide. We use the global warming potentials developed by the Intergovernmental Panel on Climate Change to combine the three gases into tons of carbon dioxide equivalent. We believe this gives the most complete and accurate reflection of the impact of each vehicle's energy use on the global climate.

Numerous assumptions and calculations are necessary to estimate full fuel-cycle greenhouse gas emissions in carbon dioxide equivalents. So, estimates from different sources will vary. Our estimates are taken from the U.S. Department of Energy's GREET Model developed by Argonne National Laboratory.