In the high-efficiency world of green technology, acronyms abound. The 2011 Chevy Volt adds another to the fray with its E-REV, standing for Extended-Range Electric Vehicle. And far from PR frippery on this, the day of the Volt's very public birth, E-REV is a very significant automotive accomplishment.
First of all, the Volt's driven wheels are always and only powered by electricity. Unlike a gas/electric hybrid, which uses either electric propulsion or a mix of electric and gasoline propulsion, the Volt's drivetrain is motivated solely by electric motors. And for up to 40 miles of driving, its onboard batteries provide all the juice needed for city driving, highway driving, and even max acceleration runs. When those onboard battery packs are nearing depletion, a small gasoline/E85-powered engine generator both provides electricity for the car's electric motors and recharges the battery packs. The Volt can be driven in this mode for several hundred additional miles before requiring a stop. This setup is similar to a diesel electric locomotive, which uses its huge diesel engines only to generate electricity to drive the motors that motivate the train forward.
The second part of the Volt story is plug-in charging of its battery pack. Using a 240-volt household outlet (like the one for a heavy-duty A/C unit) enables complete charging of the Volt's battery pack in three hours, while a standard wall outlet at 120 volts charges the Volt's battery pack in about eight hours. GM says charging times will be less if the battery has not been fully depleted and adds that a full Volt charge will cost some 80 cents, less energy consumption than the average home's refrigerator and freezer consume in a day. And far less than a drink from the local gourmet coffee and sugar dealer.
More than 220 lithium-ion cells in the Volt's battery pack send juice to an electric drive unit that delivers the equivalent of 150 horsepower and a generous 273 pound-feet of torque (generated at zero RPM, as in all electric motors). Top speed is a reported 100 mph. GM rates the Volt's efficiency at about 2 cents per mile, compared to 12 cents/mile for gasoline sold at $3.60 per gallon. Charging the Volt during peak electricity rates, the vehicle costs approximately one-sixth the price of a gasoline vehicle, says GM. Charging it during off-peak hours will yield even greater cost savings over gasoline vehicles.
What we want to know is what vehicle was GM using for comparison, a HUMMER or a Honda? And when the gasoline generator kicks in, just how much does efficiency drop? Regardless, the promises of Chevy's Volt are profound. If they can work out the lithium-ion kinks in time to bring this vehicle to market as promised in 2011, and if it is moderately enjoyable to drive and as quiet and refined as promised, this might very well be a vehicle that helps save GM.--Colin Mathews