The Chevy Volt made its West Coast debut at the AltCar Expo & Conference in Santa Monica, Calif., drawing curious and enthusiastic onlookers Friday.

General Motors unveiled the plug-in hybrid electric car in Detroit last week as part of a celebration of its 100th birthday. For the AltCar Expo, which showcases commercial and concept cars, GM shipped the same silver Volt from Detroit and parked it inside the Santa Monica Civic Auditorium (see photos to the right).

GM plans to launch the Volt in November 2010. The automaker has engineered the Volt to drive using only the electric motor, but the four-seat car will use a small gasoline engine to generate electricity to help power the motor for longer distances. The design is different than today's hybrid-electric cars, such as the Toyota Prius, which are propelled by both the electric motor and the gasoline engine.

The silver Volt is the only one in North America, said Shad Balch, a GM spokesman at the expo. The carmaker is road-testing the Volt engine and lithium-ion battery pack in Detroit by transplanting them into the body of Chevy Malibu.

The model on display at the expo doesn't have its battery pack or the gasoline engine, Balch said. It does have a small battery pack to move the motor.

The regular lithium-ion battery pack would weigh 400 pounds and would be located in a T-shape beneath the seats, Balch said. It would take about six hours to recharge, at an estimated cost of 2 cents per mile.

In the current version, electrical charging would take place near the driver-side door, but GM is considering making it possible to charge from the passenger side as well.

The engineless Volt wasn't available for a test drive, for obvious reasons, but onlookers could open the driver-side door to peek inside the car. Some lucky ones got to sit in the driver seat to get closer views. Volt drew admiring nods and comments from expo attendees, many of them wanted to know how much it would cost to own one.

GM hasn't announced the pricing yet, but GM executives have talked about a price tag of under $40,000. GM CEO Rick Wagoner had previously said that the company would like to sell the Volt for less than $30,000.

The exhibit took place the same day that GM said it has received a preliminary nod from the U.S. Environmental Protection Agency to certify the Volt as the first electric car that can get 100 miles per gallon.

GM had tussled with the EPA over fuel-economy testing and, to a large extent, over whether the Volt will be considered an electric car or a hybrid. The EPA had initially considered requiring the Volt's battery to be fully charged throughout the test.

Keeping the Volt's battery fully charged would require its gasoline engine to be running pretty much the entire time, which would likely result in a fuel economy of 48 miles per gallon. The Volt can go 40 miles on a fully charged battery before the gasoline engine has to kick in to replenish it.

The Prius, meanwhile, has a fuel efficiency of 48 miles per gallon in the city and 45 miles per gallon on the highway. The car uses a nickel-metal-hydride battery, which can last only 2 miles per charge.

An EPA spokeswoman told Bloomberg that the agency hasn't finalized its testing policy for plug-in hybrid electric cars yet.

The AltCar Expo will end on Saturday. Click here to see slideshow featuring other green cars.