.. miles per gallon.
The Volt has a combined (electric-only mode and gasoline-only mode) EPA-rating 60 mpg.
By contrast, the Toyota Prius has a rating of 51 MPG in the city and 48 on the highway.
The EPA's numbers suggest that General Motors (gasp) exaggerated the Volt's performance.
Here's the article.
(Edmunds Inside Line) DETROIT -- The 2011 Chevrolet Volt, the industry's first mainstream plug-in hybrid, has been rated by the EPA at 93 MPGe in electric-only mode and 37 MPG in gasoline-only mode. The EPA also has issued a "combined composite" rating of 60 MPG for the Volt.The EPA numbers are well short of General Motors' initial claim last summer that the Volt would achieve a mileage rating of 230 mpg -- a claim that the government agency was quick to pooh-pooh.
Read more on the Chevy Volt.

Anybody that trusts GM or the Government's numbers on the Volt's economy is a fool.
No one would even buy one were it not for the bribes, er rebates.
Then there's the electric brown-outs to come.
When the feds are involved, you can be sure of getting a boondoggle.