General Motors' Chevrolet Volt electric car, set for release into showrooms in 2010, has been given an official EPA rating of more than 230 miles per gallon of gasoline in city driving and a combined city-highway average fuel economy of more than 100 MPG., the automakers' Chief Executive Officer Fritz Henderson said on Tuesday.

The range will make the Volt the first mass production vehicle that would exceed triple-digit gas mileage , GM said in a post on the Volt's blog today.

“From the data we’ve seen, many Chevy Volt drivers may be able to be in pure electric mode on a daily basis without having to use any gas,” said Henderson in a statement. “EPA labels are a yardstick for customers to compare the fuel efficiency of vehicles. So, a vehicle like the Volt that achieves a composite triple-digit fuel economy is a game-changer.”

The Volt is designed to run for 40 miles from a single charge of a lithium-ion battery, and as the battery empties an engine kicks in recharging the battery and powering the car.

GM said about 8 of 10 Americans drive fewer than 40 miles a day, according to Department of Transportation data.

GM said the Environmental Protection Agency developed a new fuel economy methodology to measure the range of electric vehicles. It said the methodology assumes in city driving the car will mostly operate on electricity but some degree of gas operation is taken into account. The automaker also said the petroleum equivalence of electricity and a utility factor weighing in the population’s driving behavior are also included in the calculation.

The Volt will be launched in November 2010, GM said in April. The company has allocated about $1 billion to develop the electric sedan which will hit the market as a top competitor for Toyota Motor Corp.'s hybrid Prius, which is the top seller of its kind. The Volt is expected to cost around $40,000.

In comparison, the Toyota Prius gets 51 miles per gallon in the city and 50 mpg in a combined city-highway driving.

GM, which recently exited from the corporate bankruptcy, has said the Volt is a symbol needed to demonstrate it is changing its ways to more efficient cars, in part because it has also been pressured by the government to move to more fuel efficient models that contribute to Obama's administration push for lower carbon emissions and less need to import oil.