 In 2008 , General Motors was concerned about how the United States Environmental Protection Agency ( EPA ) would test the Volt to determine its official fuel economy rating . The controversy centered on whether , by including a gasoline engine , the Volt should be classified as a hybrid rather than an electric car as claimed by General Motors . If tested with the same EPA tests used by other hybrids , the Volt 's EPA fuel economy rating would be around 48 mpg @-@ US ( 4 @.@ 9 L / 100 km ; 58 mpg @-@ imp ) due to the current EPA test for hybrids disallowing vehicles from boosting their mpg rating using stored battery power . General Motors stated that the Volt is an entirely new type of vehicle which the EPA 's current fuel economy tests were not suited to rate and that a new test should be devised for this emerging class of hybrid @-@ electrics . General Motors also advocated for a more simplified mpg calculation method to take into account the range of a plug @-@ in hybrid while running solely on electricity . Because the Volt can travel 40 miles ( 64 km ) on batteries alone , GM argued that most drivers with a daily commute of less than that distance would drive only in electric mode , so long as they recharged their vehicle at work or at home overnight . 
