Detroit Show: Electric Volt Concept

General Motors is back in the electric car business. The Volt concept, which just made its debut at the North American International Auto Show in Detroit, is what GM calls an "EV range-extender." The lithium-ion battery pack will fully recharge from a 110-volt outlet in about six hours, and power the Volt for about 40 miles - standard electric car fare. Here's where it gets interesting: Driving for more than 40 miles prompts a 1.0-liter three-cylinder engine to fire up and run at constant speed, spinning a generator that recharges the batteries. A 60-mile drive - with the engine running to maintain charge - yields a total fuel economy of 150 mpg. When taking advantage of the Volt's flex-fuel capabilities to run on E85 fuel (85 percent ethanol, 15 percent gas), total gasoline fuel economy for the same drive is 525 mpg.

This propulsion system, called the E-flex System, is highly adaptable. GM says that future iterations of the concept will replace the engine with a hydrogen-powered fuel cell. Engines that run on pure ethanol (E100) and biodiesel are options too. The four-seat Volt is about the size of the Chevy Cobalt, but looks much more aggressive with its large wheels pushed to the extreme corners of the car. A 640-mile total driving range means the Volt is not likely to strand its drivers - a fear that plagued GM's earlier, pure-electric EV1. Like that car, however, the Volt's future is dependant upon the speed at which battery technology advances. GM admits that a production-ready battery pack needed to make the Volt a reality probably won't be available until 2010 or 2012.