Volt electric car may earn 230 mpg rating

DETROIT, Aug. 11 (UPI) -- The Chevrolet Volt electric car may earn a fuel-efficiency rating of 230 miles per gallon for city driving, U.S. automaker General Motors Co. said Tuesday.

GM has been working with the Environmental Protection Agency for several years on how to rate the mileage of the Volt, which runs on electricity, but includes a gas-powered engine that generates extra electricity for trips longer than 40 miles, CNNMoney.com reported.

Essentially, the Volt will drive the first 40 miles on an electric charge alone. After that, the gas-powered motor kicks in.

Longer trips would change the equation. A 300-mile trip would reduce fuel efficiency to 62.5 miles per gallon.

Nevertheless, GM Chief Executive Officer Fritz Henderson called the Volt a potential "game-changer for us."

GM is currently producing 10 Volts a month, but plans to have the car reach showrooms in late 2010.