After more than two decades, the EPA is finally revising its fuel economy ratings system to more accurately reflect real world performance. The ratings, which start in the 2008 model year, will drop most vehicles' ratings by around 10 percent, but hybrid vehicles could see their MPG drop by more than 15 percent.
The new ratings factor in drivers who accelerate quickly, driving in cold weather, and driving with the air conditioning on. According to the EPA, the ratings for the Toyota Prius are likely to drop from 55 combined city/highway MPG to 46, or about 16 percent. The Honda Civic Hybrid EPA rating will likely drop by about 15 percent. At the other extreme, the Hummer will drop from 17 to 15 MPG.
The new rating system will likely make hybrids less appealing to some buyers, who might be more reticent to spend extra for a car that gets less than 50 mpg. It could also force the federal government to revise the hybrid tax credit system which compares vehicles relative to their class in fuel economy.
Correcting the testing process is long overdue. As I reported three years ago, the EPA tests were generous in their assessment of hybrid performance. Of course, as anyone who has every owned a hybrid or has carefully monitored their fuel economy knows, your mileage will vary greatly depending on your driving style. Those who don't use the AC much and know how to slow down and accelerate will probably see several MPG better than the EPA suggests.
