The first 100-mpg car

A car that gets 100 miles per gallon? It may not be as far a way as you think.

General Motors said it has reached a preliminary agreement with Environmental Protection Agency regulators that clears the way for the Chevrolet Volt, an electric vehicle that could be recharged at home or with a 1.4-liter gasoline engine, to be certified as the first 100-mpg car.

Even though the Volt is classified as an electric car, GM will still be able to claim it's the most fuel-efficient vehicle because a gasoline-powered engine would take over if the sedan exceeded the 40-mile range of its battery.

Earning a 100-mpg certification would give the country's biggest automaker the holy grail its industry first envisioned during the oil shocks of the 1970s. Detroit-based GM's sales of pickup trucks and sport-utility vehicles collapsed this year as gasoline topped $4 a gallon.

"It's a huge milestone to beat 100 mpg. It's bragging rights," said Rebecca Lindland, an analyst at Global Insight in Lexington, Mass. "To many people, GM is just about gas-guzzling SUVs. They never get credit for fuel economy. If Toyota were doing the Volt, they would be having parades and waving flags."

While the EPA won't confirm how it gauges fuel economy of plug-in models until testing methodology is complete, Tony Posawatz, vehicle-line director for the Volt, said the agency preliminarily agreed to a method that will produce a rating of at least 100 mpg for the Volt.

But depending on assumptions in the test method, Volt could get 120 mpg to 200 mpg, said Michael Duoba, a research engineer at Argonne National Laboratory in Argonne, Ill., and chairman of the Society of Automotive Engineers committee trying to develop fuel-economy tests for plug-in cars.

"It's a new process"

The EPA "hopes to have a final policy soon," said spokeswoman Catherine Milbourn.

The four-passenger Volt, scheduled to go on sale in November 2010.

Obtaining a 100-mpg rating will require the EPA to develop a new way of measuring fuel efficiency for a car that's likely to rely more heavily on electric than internal-combustion power, according to GM's Posawatz. The automaker promised to share mileage data captured from the Volt's onboard computers to verify real-world performance if EPA will grant the certification now, he said.

"It's a new process. No one has done a vehicle like this before," said Posawatz. "We would like to have 80 percent of the people get better than the [EPA rating] label."

Other efforts

The government- and industry-backed Partnership for a New Generation of Vehicles tried to create an 80-mpg auto in the 1990s. The group disbanded in 2001 after failing. The Progressive Automotive X Prize is offering $10 million to the first team to produce a 100-mpg vehicle that passes its tests and can be commercially produced — though GM is not listed among the contest competitors.

Toyota's hybrid Prius is the highest-rated car on the road today, achieving 48 mpg in the city and 45 mpg on the highway. It has a 1.5-liter gasoline engine, isn't rechargeable at an electric outlet and can drive only 2 miles on its battery, according to the company, which leads global sales in the category. Companies that offer aftermarket plug-in conversions for the Prius have been making anecdotal claims of 100 mpg.

Toyota said it may launch a factory plug-in model for 2010 with an all-electric range of at least 10 miles, and that may have difficulty beating 100 mpg in the same tests, Duoba said.

"It's too early to say what the overall miles-per-gallon figure is going to be" on the plug-in Prius, said John Hanson, a spokesman for Toyota City, Japan-based Toyota.

Honda's FCX Clarity fuel-cell car, leased since July to celebrities in Los Angeles including actress Jamie Lee Curtis, is rated at 72 mpg via a formula that converts hydrogen fuel into the equivalent of gasoline efficiency ratings. Honda hasn't announced full-scale production for the model.

As with all automakers selling in the U.S., GM must increase the average mileage of its fleet as much as 40 percent to 35 mpg by 2020 to comply with new federal standards. U.S. auto companies estimate they'll spend $80 billion to $100 billion to meet the new mandate.