Hybrid vehicles pose mileage rating problem

Los Angeles Times : How do you gauge fuel economy when there’s no gasoline? asks Tiffany Hsu, writing for the Los Angeles Times. In her article, Hsu details the difficulties encountered by the Environmental Protection Agency, which has had to come up with a way to rate the new hybrid cars. Traditionally, the fuel economy rating for vehicles with internal combustion engines has been calculated from emissions generated during a series of tests. Because the Nissan Leaf runs entirely on a battery, the EPA developed a miles-per-gallon-equivalent rating. Things got more complicated with the Chevrolet Volt, a hybrid plug-in that switches to gasoline when its electricity runs out; the EPA gave the Volt multiple ratings, depending on when it runs on just electricity, just gas, or both. In addition, the EPA’s rating may end up sharing sticker space with those of other entities, such as the Federal Trade Commission and the automakers themselves, which may use different testing systems.