Unlimited mpg? The great Volt debate

At some point, the EPA will have to give GM’s new electric car a fuel-economy rating. It won’t be easy.

NEW YORK (CNNMoney.com) — How do you measure the fuel economy of an electric car? Is it the equivalent of 80 miles per gallon? 8,000?

Turns out it’s a thorny issue – and General Motors is currently in long-term discussions with the Environmental Protection Agency to develop a standard.

The decision could make a big difference for GM (GM, Fortune 500), which is expected to unveil the Volt this week. The automaker’s first long-range electric car could hit showrooms by 2010. The compromise between GM and the EPA could have a major impact on how effectively the Volt is marketed.

Discussions are still a long way from resolution, but progress is being made, said GM spokesman Kyle Johnson. “This is a very analytical and a very thoughtful process,” Johnson said.

The EPA will say only that it is “still developing its policy for testing, measuring, and reporting fuel economy for plug-in electric hybrid vehicles.”

CNN