General Motors unveiled the Chevrolet Volt this morning, revealing a car that is much sleeker than the angular concept we saw almost two years ago. It's the strongest evidence yet that the range-extended electric car is on track to appear in showrooms by the end of 2010, and a good sign that GM may stick around more than a couple years past its hundredth birthday.

CEO Rick Wagoner pulled the sheet off the Volt during GM's centennial celebration in Detroit, hailing it as a technological leap and a new direction for a company – and an industry – facing an uncertain future.

"Revealing the production version of the Chevy Volt is a great way to open our second century," Wagoner said. "The Volt is symbolic of GM's strong commitment to the future ... just the kind of technology innovation that our industry needs to respond to today's and tomorrow's energy and environmental challenges."

The Volt is not a Johnny-come-lately second-rate Prius. It’s a technological step forward and a bit of a surprise from a company that has for decades been known for evolution, not revolution. The Volt's 17-inch wheels are driven by an electric motor that gets its juice from a T-shaped battery with 220 lithium-ion cells. GM says it's good for 40 miles of zero-emission electric driving. The small gasoline engine under the hood acts only as a generator, charging the battery as it approaches depletion and eliminating the "range anxiety" that make EVs a tough sell for road-trip-lovin’ Americans.

The sleek, rounded car Wagoner showed off today shares little family resemblance with the angular concept he unveiled in 2007. The radical redesign was borne of necessity – maximizing aerodynamic efficiency is essential to squeezing every last mile from the battery, and the original design was about as slick as a brick.

After discovering the concept car’s wretched drag coefficient of .43 – roughly the same aerodynamic efficiency as a Chevrolet Silverado pickup – GM's designers and engineers spent more than 1,000 hours in the wind tunnel reworking the exterior. What they emerged with is, according to GM, more aerodynamic than the Toyota Prius or the Honda Civic Hybrid. "We spent three times longer on this car than any other car [in GM’s history]," says Nina Tortosa, the engineer who oversaw wind tunnel testing. "It will be one of the most aerodynamic cars out there."

Some will look at the Volt and see the Prius, and aerodynamic necessity meant the two cars would have similar silhouette – though the two vehicles are based on different technologies, they share the same constraints: They’re small 5-door sedans designed for maximum aero efficiencies. The laws of physics and the properties of aerodynamics give designers only so much leeway.

Still, GM insists the production model shares many of the same styling cues as the concept – the grille, the "athletic stance," the crease along the side and the mirrors. The Volt also is longer, lower and wider than the Prius. The nose is longer, the roof flatter and the tail lower. "The Prius doesn't have stance," says Bob Boniface, Volt lead designer. "It's got a big body on little wheels. The Volt's got a wide, low stance."

Reaction to this mythic stance has been mixed, with many people condemning it as a Prius clone. A poll of 1,388 people by fanboy-site GM-Volt.com found 57 percent preferred the concept. But the site’s founder, New York neurologist Lyle Dennis, likes it. "I think it has a clean look," he says. "The concept was more extreme in appearance than a mainstream car could be."

Chelsea Sexton, director of the EV advocacy group Plug-In America, agrees. "I definitely liked the more aggressive design of the concept, but it wasn't realistic from an aerodynamic perspective," she says. "The redesign will still capture a lot of people aesthetically, but just as much, I think, from a functionality and user experience perspective – especially the interior."

GM seems to have taken a page from the Apple design playbook when designing the interior of the Volt. Its most prominent feature is an LCD touch screen to control the climate and infotainment systems and a smooth control panel with what resemble click wheels.

Of course, the car Wagoner unveiled today was little more than a full-size model. Though the design of the exterior is now finalized, GM still has to perfect the innards to make a working car. They key to that is nailing the batteries, and GM has its engineers testing batteries around-the-clock. Bob Lutz, VP of global development and the guy cracking the whip to keep the Volt on schedule, says the batteries are performing "flawlessly" and "it's almost scary that we aren't seeing any problems with them." Still, it remains to be seen whether the batteries will deliver on their promised range and survive 10 to 15 years of abuse at the hands of American drivers.

GM is road-testing the Volt's drivetrain in a fleet of converted Chevy Malibus (see, not all of them are rental cars), and company execs say we'll see production prototypes on the road next year. It's an aggressive timeline, but industry analysts say GM is in good shape to meet it, and the company reportedly plans to spend another $400 to $500 million getting the car on the road.

"They're throwing lots of money at it, and they're moving forward," says Aaron Bragman of Global Insight. "Where they are in terms of testing, two years seems like an achievable goal. They're on track."