1

Regulatory

Announcement

Offi ce of Transportation

and Air Quality

EPA420-F-06-009

January 2006

EPA Proposes New Test Methods for 

Fuel Economy Window Stickers

The U.S. Environmental Protection Agency (EPA) is proposing new test 

methods for calculating the fuel economy estimates that are posted on 

the window stickers of new cars and trucks. The city and highway miles 

per gallon (MPG) estimates help consumers compare the fuel economy 

of different vehicles.

Although no single test can ever account for the wide variety of driving 

conditions and styles, EPA’s proposal will bring the MPG estimates closer to the fuel economy consumers actually achieve on the road. The new 

MPG estimates will take effect with model year 2008 vehicles, which will 

be available in dealer showrooms in the fall of 2007.

Background / Current Tests and Methods

The city and highway MPG estimates have been provided to consumers since the 1970s as a tool to help shoppers compare the fuel economy 

of different vehicles. Currently, EPA relies on data from two laboratory 

tests to determine the city and highway fuel economy estimates. The test 

methods for calculating these estimates were last revised in 1985, when 

the fuel economy derived from the two tests were adjusted downward—

10 percent for city and  percent for highway —to more accurately 

refl ect driving styles and conditions.

The city and highway tests are currently performed under mild climate 

conditions (75 degrees F) and use acceleration rates and driving speeds 

that EPA believes are generally lower than those experienced by drivers 


in the real world. Neither test is run with the use of accessories, such as 

air conditioning. The highway test has a top speed of 60 miles per hour, 

and an average speed of only 48 miles per hour.

Since the mid-1990s, EPA’s emission certification compliance regulations have required the use of three additional tests which capture 

a much broader range of real-world driving conditions; specifically: 

high-speed, fast-acceleration driving and the use of air conditioning and 

colder temperature operation (20 degrees F). Not only do these conditions impact the amount of air pollutants a vehicle emits, they also have 

a significant impact on a vehicle’s fuel economy. However, they are not 

currently required to be used to measure fuel economy.

The Proposed New Methods to Determine Fuel 

Economy 

EPA is proposing to incorporate these tests into the methods used to 

determine the fuel economy estimates posted on the window stickers of 

new cars and light trucks. For the first time, the EPA fuel economy estimates will reflect vehicle-specific data from tests designed to replicate 

three real-world conditions that can significantly affect fuel economy: 

high speed/rapid acceleration driving, use of air conditioning, and cold 

temperature operation. Previously, these conditions were accounted for 

by across-the-board adjustments, rather than by vehicle-specific testing.

EPA is also proposing that the fuel economy estimates reflect other conditions that affect fuel economy, such as road grade, wind, tire pressure, 

load, and the effects of different fuel properties. The fuel economy for 

each vehicle model would continue to be presented to consumers as city 

and highway MPG estimates.

Auto manufacturers would be required to perform the fuel economy 

testing specified in EPA’s proposal. In the 2008 model year, the new 

methods would be used to determine the estimates. In 2011, a provision 

would take effect that would require manufacturers to perform additional 

cold temperature, air conditioning and/or high speed/rapid acceleration driving tests for some vehicles that may be more sensitive to these 

conditions. The additional testing would ensure that the fuel economy of 

those vehicles is more precisely captured. EPA is proposing to delay this 

additional testing until 2011 in order to provide enough time for manufacturers to plan for the added testing responsibilities. Nevertheless, 

beginning in 2008, the fuel economy for those sensitive vehicles would 

still reflect enough of the above effects such that consumers can make 

good comparisons.


How Fuel Economy Estimates Will Change from 

Today’s Labels

Under EPA’s proposal, the new fuel economy estimates would be lower 

for most vehicles. This is not because auto makers have designed the 

same vehicles to be less fuel efficient—it is because our new test methods take into account factors that have been missing or not fully accounted for in the current tests. Because some vehicles are more sensitive to these factors than others, the impact of the proposed changes will 

vary from vehicle to vehicle. The city MPG estimates for conventional 

(non-hybrid) vehicles would drop on average by about 10-20 percent 

from today’s labels, while the highway estimates would drop by about 

5-15 percent, depending on the vehicle.

For hybrid vehicles, the city MPG estimates would drop 20-30 percent 

from today's labels. For highway MPG estimates, the change is about the 

same as for conventional vehicles. The nature of current hybrid technology–the addition of a battery as a second source of on-board power, 

sophisticated control systems, and sometimes a smaller engine—makes 

a hybrid’s fuel economy more sensitive to certain factors, such as colder 

weather and air conditioning use. However, many hybrid models will 

remain among the most fuel-efficient vehicles on the market.

Laboratory Tests Reflect Real-World Conditions

It is essential that EPA’s fuel economy estimates continue to be derived 

from controlled, repeatable laboratory tests to enable a standardized or 

“level playing field,” comparison between all vehicle models. However, 

the underlying calculations proposed to determine the estimates are 

based on data from real-world driving behavior and conditions. Laboratory testing also preserves EPA’s ability to confirm the results of manufacturers’ testing.

Auto makers will continue to be responsible for performing the fuel 

economy testing and calculating the label MPG estimates. EPA will 

continue to confirm the manufacturers’ test results by performing audit 

testing at its National Vehicle and Fuel Emissions Laboratory in Ann 

Arbor, Michigan.

Since everyone drives differently and under varied conditions, there is 

no test that could perfectly predict the fuel economy that every driver 

will get. With any estimate, there will always be times when a driver’s 

actual fuel economy will be higher or lower. However, EPA’s proposal 

will do a better job of bringing the estimates on the window sticker 

closer to people’s real-world fuel economy experience.
Fuel Economy Label Design

EPA is also proposing to revise the format and text of the fuel economy 

window sticker that appears on new automobiles. This is being done to 

more clearly convey the fuel economy information to consumers. The 

proposal includes four label options under consideration. The label options are also available at www.epa.gov/fueleconomy.

No Impact on CAFE

EPA’s proposal has no impact on the Corporate Average Fuel Economy 

(CAFE) program. There are separate regulations concerning the test 

methods and procedures to determine the fuel economy values under the 

CAFE program, which is administered by the Department of Transportation.

Public Comment

EPA is providing a 60-day comment period on the entire proposal, including the new fuel economy testing methodology and label redesign. 

Also, EPA will hold a public hearing after the proposal is published in 

the Federal Register. For more details about how to comment or to attend the public hearing, please see the Federal Register notice or go to 

www.epa.gov/fueleconomy.

For More Information

You can access documents on this rulemaking on EPA’s Office of Transportation and Air Quality Web site at:

www.epa.gov/fueleconomy

For further information, please contact the Assessment and Standards 

Division at:

U.S. Environmental Protection Agency

Office of Transportation and Air Quality

 2000 Traverwood Drive

Ann Arbor, MI 48105

Voice-mail: (734) 214-4636

E-mail: asdinfo@epa.gov