http://www.greencarreports.com/news/109 ... -at-39-mpg
2012 Chevrolet Volt Racks Up 250,000 Miles, One-Third Electric, Rest At 39 MPG
Since taking delivery of his Volt on March 28, 2012, Belmer calculates lifetime "blended" fuel economy of 59.4 mpg (both electric and gasoline miles). That's better than the rated 50 mpg combined of the most efficient car without a plug sold in the U.S., the Toyota Prius hybrid. When operating on gasoline alone, he has averaged 38.6 mpg, slightly higher than the EPA rating. So far the Volt seems to be holding up well. At 200,000 miles, Belmer said there has been no apparent loss in battery capacity. His maintenance primarily consists of oil changes every 38,000 miles, and tire rotations at 10,000 miles.