The Hybrid Illuuusion

The EPA has modified it's fuel efficiency test in order to give more realistic results for hybrid cars.

The two top-selling hybrid vehicles, the Prius and Honda's Civic Hybrid, will lose 12 and 11 miles per gallon respectively from their city driving estimates. Other vehicles are downgraded between 2 and 4 mpg (see chart).

Overall, vehicle city mileage estimates dropped by about 12 percent, and some vehicles are expected to be rated 30 percent lower, according to EPA documents.

The new EPA tests factor in real-world conditions such as speeding, varying weather and lead-footed driving. Vehicles like hybrids with smaller engines pay a higher penalty during the acceleration test, as well as the tests that simulate going up a hill and maintaining highway speeds.