GM CEO Fritz Henderson addresses the media at GM's Tech Centre in Warren, Mich., during a news conference regarding the Chevy Volt's fuel consumption rating on Tuesday. (Gary Malerba/Associated Press)

General Motors Co. expects its Chevrolet Volt rechargeable electric car will have a fuel consumption rating of around 1.0 L/100 km for city driving, or 230 miles per U.S. gallon, a figure that is about four times better than the most fuel-efficient auto currently on the market, the Toyota Prius.

The figure has yet to be confirmed by the U.S. Environmental Protection Agency, whose approval GM needs in order to advertise that consumption.

But GM tested the vehicle using guidelines drawn up by the EPA for calculating consumption for extended-range electric vehicles, said GM's vehicle line director for the Volt, Tony Posawatz on Tuesday.

Toyota's Prius, the most efficient car now sold in Canada and the U.S., consumes about 4.0 L/100 km for city driving. It is a gas-electric hybrid that runs on a small internal combustion engine assisted by a battery-powered electric motor to save gasoline. But the Volt is designed to run largely in electric mode.

"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," Fritz Henderson told the Wall Street Journal on Tuesday.

"EPA labels are a yardstick for customers to compare the fuel efficiency of vehicles," he said, adding that achieving the EPA-sanctioned 1.0 L/100 km figure would be "a game-changer."

65 km per charge

The Volt, due in showrooms late next year, can go 65 kilometres on a single charge from a home electrical outlet and has a small internal combustion engine to generate electricity beyond that.

It is expected to retail for about $40,000 US — a price that observers said could be prohibitive to many buyers, even if gas prices rise.

The price is expected to drop with future generations of the Volt, but GM has said government tax credits and the savings on fuel could make it cost-effective.

Last month, Ontario increased the maximum rebate for purchasing a plug-in hybrid vehicle to $10,000.

Figures for the Volt's highway and combined city/highway consumption have not yet been calculated, Posawatz said. But those figures are expected to be worse than the city driving numbers because the engine runs more on longer highway trips.

With files from The Associated Press