2011 Chevrolet VoltEnlarge Photo
What kind of fuel economy will buyers of the upcoming Chevy Volt be able to expect when it hits dealerships (in theory) this fall? We have no idea. Neither does the Environmental Protection Association, or, for that matter, Chevrolet engineers. But it won't be the 230 mpg the company triumphantly touted last August.
In GM's defense, the company arrived at that figure using a proposed formula provided by the EPA. This week, however, the EPA announced that it won't ever use that formula to measure the fuel economy of cars like the Volt. The formula was always a bit of a farce -- Nissan happily pointed out that its all-electric Leaf would have been rated for 367 mpg under the same rules, and the Leaf doesn't even have a gasoline engine.
Experts in the auto industry and the federal government have been trying to arrive at a meaningful way to measure the fuel economy so-called Extended-Range Electric Vehicles (E-REVs) like the Volt for more than a year. The Volt isn't a simple hybrid. It isn't purely an electric car, either. It operates as an electric car until its batteries are depleted to a certain point (about 30 percent of total charge), then recharges them with a small gasoline engine.
That engine, however, doesn't power the wheels. Instead, it acts as a generator, recharging the car's batteries.
According to Chevrolet engineers, most Volt owners will get about 40 miles out of their cars in electric-only mode, and use gas only if they travel more than that distance before plugging the car in to charge. Since the average American travels less than 40 miles per day, GM says, many Volt owners may rarely use gasoline.
Chevy hasn't published figures on how fuel-efficient the Volt will be once that generator is running. It may actually prove easier to publish an accurate number for the Volt than for most cars. Since that generator operates only to recharge the battery, drivers won't be able to burn too much gas with jackrabbit starts and hard braking followed by brisk acceleration, or conserve gas by accelerating gently and feathering the brake pedal. While the EPA estimate for your current car may or may not be accurate based on your driving style, the EPA's estimate for the Volt should be much more reliable.
But we won't know what it is for some time. The agency now says it hopes to release a formula for determining the mpg of E-REV cars later this year before the Volt goes on sale in November.