 When introduced in December 2010 , the 2011 Volt was the most fuel efficient car sold in the American market in the compact class , with a combined gasoline @-@ electricity fuel economy of 60 mpg @-@ US ( 3 @.@ 9 L / 100 km ; 72 mpg @-@ imp ) equivalent ( MPG @-@ e ) , until it was surpassed by the 2012 Ford Focus Electric in February 2012 . The all @-@ electric Focus has a combined fuel economy of 105 mpg @-@ US ( 2 @.@ 2 L / 100 km ; 126 mpg @-@ imp ) equivalent ( MPG @-@ e ) . Nevertheless , the Volt remained as the most fuel efficient car with an internal combustion engine available in the United States until May 2014 , when the BMW i3 REx replaced the Volt as the most efficient EPA @-@ certified current year vehicle with a gasoline engine , with a combined gasoline @-@ electricity fuel economy of 88 mpg @-@ US ( 2 @.@ 7 L / 100 km ; 106 mpg @-@ imp ) equivalent ( MPG @-@ e ) . 
