A week ago, General Motors revealed its new plug-in hybrid Chevy Volt, along with the claim that the $40,000 car will get 230 miles per gallon.
It's a bold and slightly ironic claim from the company that's credited with killing the electric car. I'm willing to let bygones be bygones, and I'm thrilled to see an American car manufacturer step up to the plate with a car that really does reduce its driver's dependence on fossil fuels. But the claims raise some questions: How do you measure fuel efficiency and fossil fuel consumption when a vehicle is being powered by a plug? If the local source of energy is a coal-fired power plant, how should that be calculated into fuel efficiency, and how should driving style and location be considered in calculating fuel efficiency for an electric car?
As Peter Whoriskey points out in a Washington Post article, if a driver only drives 30 miles a day before recharging, and the battery range of the vehicle is 40 miles, then on could claim "infinite" fuel efficiency. In fact, you could drive cross country without using any fuel if you stopped to recharge every 40 miles. But you can't drive from Boston to Montreal on a single gallon of gas. GM calculates the cost of the electricity to power the vehicle at about $0.03 per mile.