General Motors Co. says its long-awaited Chevrolet Volt plug-in hybrid is expected to achieve fuel economy of 230 miles per gallon in city driving.
That would give the Volt, which is expected to arrive in showrooms late next year, by far the highest fuel efficiency rating of any car now rated by the Environmental Protection Agency. The current EPA mileage leader is the Toyota Prius hybrid, which is rated at 51 mpg in city driving.
The Volt is designed to run on electric power only for about 40 miles, after which a small gasoline engine kicks in to recharge the battery, giving it a total range of more than 300 miles. The battery can be recharged by plugging in to a home outlet.
GM's estimated mileage rating for the Volt is based on city driving, where it can take full advantage of its all-electric capability. Highway mileage would be lower because it would require more work from the gasoline engine.
"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 Tuesday.
The automaker's fuel economy estimate hasn't been confirmed by the EPA, which is developing a new methodology for calculating fuel economy ratings for cars that can travel significant distances powered only by electricity. GM said it used the EPA's preliminary guidelines in developing its mileage estimates for the Volt.
The EPA publishes mileage estimates for vehicles sold in the U.S. based on city and highway driving, as well as a combined city-highway mileage estimate.
GM said it had calculated a highway mileage estimate for the Volt but didn't release the figure. The automaker said it was confident the car's combined city-highway fuel economy "will be in the triple digits."
The mileage estimate doesn't include the electricity needed to charge the Volt's nearly 400-pound lithium-ion battery, causing some analysts to question the usefulness of the number.
"EPA fuel-consumption measures are really inappropriate for the Volt," said Kevin Smith, editorial director for online automotive site Edmunds.com. "The EPA doesn't measure the energy consumed when charging the car via plug-in, and depending on your driving, that may be all the energy it needs."
That could include a lot of potential drivers. Scott Samuelson, director of the National Fuel Cell Research Center at UC Irvine, estimates that 60% of Southern Californians drive less than the Volt's 40-mile all-electric range each day.
