General Motor Co's Chevrolet Volt extended-range electric vehicle is expected to achieve city fuel economy of a wopping 100 km a litre (or around 230 miles per gallon) in city driving conditions, GM said in arelease. The figure is based on development testing using a draft EPA federal fuel economy methodology for labeling for plug-in electric vehicles, GM said.

The Volt, which is scheduled to start production in late 2010 as a 2011 model, is expected to travel up to 40 miles on electricity from a single battery charge and be able to extend its overall range to more than 300 miles with its flex fuel-powered engine-generator.

"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," GM chief executive Fritz Henderson said. "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," he added.

Nearly eight out of 10 Americans commute fewer than 40 miles a day, according to US Department of Transportation data, the release said.

"The key to high-mileage performance is for a Volt driver to plug into the electric grid at least once each day," Henderson said.

GM said the Volt's actual gas-free mileage will vary depending on the distance travelled, the load and the number of passengers they carry and how much the air conditioner or other accessories are used.