The EPA is proposing new methods to determine the city and highway MPG estimates that appear on window stickers for cars, SUVs, and pick-up trucks. These new fuel economy methods will take effect for model year 2008 vehicles, which will generally be available for sale in the fall of 2007.
The fuel economy estimates will include vehicle-specific data from tests designed to replicate three factors that can affect fuel economy: high speed/rapid acceleration, use of air conditioning, and cold temperature operation. City MPG estimates for most vehicles would drop 10 to 20 percent from current labels, depending on the vehicle. The highway estimates would generally drop 5 to 15 percent.
According to the EPA, even with improved estimates, actual fuel economy will vary since no test can account for all individual driving styles, maintenance practices, and road conditions.
The last time changes were made to the test method system was in 1985. The proposed changes will help improve the estimates to better reflect real-world driving conditions, such as higher speed limits, increased traffic congestion and more use of power-hungry accessories.
None of the changes affect the Corporate Average Fuel Economy program, which is administered by the Department of Transportation, where there are separate requirements for the test methods and procedures.