By Jennifer Kho

General Motors on Sunday unveiled a new concept vehicle that could indicate that mainstream electric cars are closer than ever.

It’s called the Chevrolet Volt, and while GM calls it an electric car (“We even toyed with the name being the EV2,” said Scott Fosgard, director of communications in powertrains), analysts and experts are calling it a “series” or “serial” plug-in hybrid.

Advocates say the design is a leap forward from today’s gas-electric hybrid cars. Builiding the Volt could help GM better cope with rising fuel prices. More importantly, the Volt could even serve as a kind of green ‘halo’ car—helping bolster GM’s image just as the Prius has buffed rival Toyota’s green credentials.

That’s because the concept unveiled at Detroit’s North American International Auto Show is propelled by an electric motor—and can run on electricity along for about 40 miles, once it’s fully charged at a standard wall outlet for six hours or so.

It’s also got a gasoline engine, which recharges the battery for longer drives. But while a normal (also called “parallel”) gasoline-electric hybrid, like the Toyota Prius, switches off between the gasoline engine and electric motor to move the vehicle, the Chevy Volt is considered a "series" hybrid because it's propelled by the electric motor alone.

All this means the Volt is a step closer to an electric car, as it can be used as an electric car by drivers with shorter commutes. It’s also is another milestone for advocates of plug-in hybrids, hybrid vehicles that can be plugged into the wall for better gas mileage. On one tank of gas and a fully charged battery, the Volt can drive 640 miles, getting 150 miles per gallon. That could take a bite out of the U.S.’s oil habit, if such cars became commercially available and widely successful.

It’s still a concept car, for now, although GM does intend to produce a plug-in hybrid. At the LA Auto Show last month, the company said it will produce a plug-in version of its Saturn Green Line Vue hybrid (See GM to Make Plug-in Hybrid), and Bob Boniface, GM’s director of advanced design, said of the Volt: “Right now, it’s a concept vehicle—until it’s put into production.”

Thilo Koslowski, a vice president and the lead automotive analyst at Gartner, said the announcement will likely start a new buzz in the hybrid market.

“For some consumers, it could mean they might never have to buy gas again,” he said. “It’s a great way to get consumers excited about another hybrid-based system, because it’s something new—the ability to plug it in and use it as an electric vehicle.”

While it’s good for GM, the company might not see a long-term advantage from being first after others come out with plug-ins, he said. After all, Toyota Motor said it was pursuing the technology in July, and Nissan Motor said in December that it would accelerate the development of plug-in hybrid technology (see GM, Nissan, Toyota Plugging In).

A Win, But When?

Still, electric-car and plug-in-hybrid advocates are calling the Volt a win.

“We commend GM for being the first out of the starting gate in the great plug-in car race of 2007,” said Felix Kramer, founder of CalCars.org, a pro-plug-in group that has converted Prius hybrids to plug-in hybrids. “GM’s announcements are the biggest victories yet for CalCars.org and other [plug-in hybrid] advocates … We can only welcome the world’s top carmaker’s embrace of electrification to move from the petroleum wasteland into the promising territory of renewable energy.”

That’s not to say advocates are fully satisfied with the announcement.

They complain GM gave no timetable for commercializing and producing the car, instead saying in a press statement that experts predict a powerful-enough battery could be production-ready by 2010 to 2012. Mr. Boniface also said he is unable to name a date, but that GM will be the first to market with a plug-in hybrid.

“This is not 50 years away; it’s much shorter than that,” he said. “It’s not like a fuel-cell vehicle where you have to rely on huge changes to the infrastructure in this country. The hurdles aren’t nearly as huge, because we’re using existing technology in a different way.”

Advocates contend the time is now. “The perfect should not be the enemy of the good,” Mr. Kramer said. “We believe GM doesn’t fully recognize how many early adopters and fleets will pay more for early [plug-in hybrids] … We want carmakers to be incremental and begin building “good enough” [plug-in hybrids].”

Key To Success: Reliability

But Mr. Koslowski said battery reliability is a key to plug-in hybrids’ success.

“If we assume the technology is completely reliable, this is something consumers would appreciate, but there have been some reliability issues in the past,” he said. “GM had some problems with its batteries, so it’s important they are reliable and consumers can use the technology easily.”

GM certainly is working on the batteries.

In an announcement Thursday, the company said it is partnering with Cobasys, a joint venture between Chevron Technology Ventures and Energy Conversion Devices, on the battery system for the Saturn plug-in hybrid SUV.

In another partnership with Cobasys, A123Systems, a startup that provides lithium-ion batteries for Black & Decker power tools (See Battery Pumps Up Power Tools, VCs Charge Up Battery Firm, Power for Power Tools), is supplying batteries for testing and evaluation in Saturn plug-in prototypes.

GM is also working on the price. While the company wouldn’t name a price, the Chevy brand is an indication “we’re not going to price it through the roof,” Mr. Boniface said.

By and large, Chevy cars range from $15,000 to $30,000, Mr. Fosgard said. “We don’t think people will pay much of a premium to look good in the [car] that Bob built; we know we’re got to get the price down to that of a normal car.”

According to a U.S. Department of Energy report released in December, plug-in hybrids are expected to cost $6,000 to $10,000 above the price of a normal car (see U.S. Could Plug In Most Cars). Currently, for plug-in conversions, the premium is $10,000 to $12,000 (see The New Plug-In Hybrids, Plug-In Hybrids Get 100+ MPG), on top of the price of a hybrid.