If the figure is confirmed by the EPA, which does the tests for the mileage posted on new car door stickers, the Volt would be the first car to exceed triple-digit gas mileage, Posawatz said.

The Volt is powered by an electric motor and a battery pack with a 40-mile range. After that, a small internal combustion engine kicks in to generate electricity for a total range of 300 miles. The battery pack can be recharged from a standard home outlet.