"General Motors Co. is touting the 230 mpg figure following early tests that used draft guidelines from the Environmental Protection Agency for calculating the mileage of extended-range electric vehicles.

The EPA guidelines, DEVELOPED WITH HELP FROM AUTO MAKERS [emphasis added], figure that cars such as the Volt will travel more on straight electricity in the city than on the highway. If drivers operate the Volt for less than 40 miles, in theory they could do so without using a drop of gasoline.