Aug. 11 (Bloomberg) -- General Motors Co. expects its Volt electric car to earn a fuel-economy rating of at least 230 miles per gallon for city driving, more than four times that of Toyota Motor Corp.’s Prius hybrid.

“It’s fascinating and it’s exciting,” said Brett Smith, an alternative technology analyst at the Center for Automotive Research in Ann Arbor, Michigan. “For a lot of consumers it may also end up being very misleading because they won’t get that mileage in the real world.”

The automaker is counting on unproven technology to leapfrog the Prius, the world’s best-selling hybrid, which starts at $22,000. GM Vice Chairman Bob Lutz said in May that the Volt would probably cost about $40,000 when it goes on sale in November 2010.

“Many Chevy Volt drivers may be able to be in pure electric mode on a daily basis without having to use any gas,” Chief Executive Officer Fritz Henderson said today.

GM said in September it reached an agreement with the U.S. Environmental Protection Agency on a testing method that would yield a rating of at least 100 mpg for the Volt, which will be able to go 40 miles (64 kilometers) on battery power before tapping an onboard gasoline engine for a recharge.

100 MPG Combined

With combined city and highway mileage, the Volt still will probably exceed 100 mpg fuel economy, Henderson said.

“At that level, you’re still doing pretty darn good,” Smith said. “It all comes down to how much people are willing to pay to get that savings over time.”

The EPA rates the Prius as the most fuel-efficient car on U.S. roads. The 2010 Prius is rated at 51 mpg in city driving and 48 mpg on the highway, according to the agency’s vehicle- efficiency Web site.

The EPA has not tested a Volt and therefore can’t confirm the fuel economy values claimed by GM, Cathy Milbourn, an agency spokeswoman, said in an e-mailed statement.

“EPA does applaud GM’s commitment to designing and building the car of the future: an American-made car that will save families money, significantly reduce our dependence on foreign oil and create good-paying American jobs.”

Real-world mileage varies depending on such things as driving style, weather and road conditions.

‘Very Realistic’

The anticipated ratings are an accurate indicator of the mileage typical drivers might get, said Frank Weber, the executive in charge of the program.

The Volt will use about 40 cents’ worth of electricity to get its overnight charge, he said. Used that way, “numbers between 150 and 300 miles per gallon are realistic” for the average driver, Weber said.

Toyota had no comment on the Volt mileage announcement, John Hanson, a spokesman, said in an interview.

GM is building about 10 Volts each week in pre-production operations, he said. It may be produced in volumes of about 60,000 annually, once it goes on sale, GM has said. Toyota sold 158,900 Priuses in the U.S. last year, 12 percent fewer than in 2007.

Unlike conventional autos and hybrids such as the Prius, the 1.4-liter engine on the Volt won’t drive the wheels. Instead, it will only power the battery, which also can be recharged at a household outlet. The car is scheduled to go on sale late next year as a 2011 model.

3 Cents Per Mile

Using new methodology being developed, GM said it expects the Volt to consume as little as 25 kilowatt hours per 100 miles in city driving. At the U.S. average cost of electricity, a typical Volt driver would pay about $2.75 to travel 100 miles, or less than 3 cents per mile, GM said in the statement today.

A traditional car that gets 30 mpg would cost 10 cents per mile to drive when gasoline sells for $3 a gallon.

The automaker, majority-owned by the U.S. government since it emerged from bankruptcy on July 10, is speeding to remake itself. Henderson has said the Volt and the development of advanced batteries are priorities for the Detroit-based company.

“It’s a fascinating time to watch the auto industry,” Smith said. “Maybe not everything is ready for prime time, but it’s getting closer.”

‘Not Yet Proven’

GM has offered its own caution about the risk associated with the Volt. The model “has not yet proven to be commercially viable,” according to a regulatory filing last week. The technology required to power the car may not be developed in time for its planned 2010 debut, the automaker said.

“Our competitors and others are pursuing similar technologies and other competing technologies, in some cases with more money available,” GM said. “There can be no assurance that they will not acquire similar or superior technologies sooner than we do.”

Nissan Motor Co.’s Leaf all-electric vehicle, which goes on sale next year, would have a fuel economy of 367 miles per gallon on a similar basis, Nissan said last week. The Leaf has a total range of about 100 miles on a full charge. The Volt has a total range of more than 300 miles, GM said today.

Chrysler Group LLC is planning to sell its first electric vehicle by the end of next year and has said it could be one of several varieties. Chrysler says its vehicles can attain the same performance as the Volt, getting the first 40 miles of range on an all-electric charge before a gasoline generator recharges the lithium-ion battery.

Ford Motor Co., which already sells four hybrid models, plans to introduce an all-electric version of its Transit Connect van next year and its Focus small car in 2011. The Dearborn, Michigan-based automaker also has said it will introduce plug-in hybrid models in 2012.

More GM Models

GM also unveiled plans for a new small rear-wheel-drive Cadillac coupe and a large Cadillac sedan to replace the STS and DTS models.

The automaker said it plans to introduce small and midsize Buick sedans and what Susan Docherty, the head of Buick, Pontiac and GMC, called a “baby Enclave,” a small SUV. GM said all were generally set for production in two to three years, while declining to give specific dates.

To contact the reporter on this story: Katie Merx in Southfield, Michigan, at kmerx@bloomberg.net; Jeff Green in Southfield, Michigan, at jgreen@bloomberg.net

Last Updated: August 11, 2009 14:58 EDT