What will fuel-economy numbers look like on the window stickers of electric vehicles coming to the US market next year?” asks Paul Weissler, in his recent article for the Society of Automotive Engineers. Trying to find the answer could short-circuit your brain.

The big numbers on the window sticker for BMW’s Mini E—currently in the hands of hundreds of consumers in a test program—are 33 in the city and 36 on the highway. But those are posted in kilowatt hours per 100 miles. The smaller text explains that the equivalent is 102 mpg city and 94 mpg on the highway.

When plug-in cars hit the US market in the next year or two, consumers will need a lot of help deciphering the efficiency figures of vehicles that carry electric fuel by the kilowatt hour rather than liquid fuel by the gallon. Nissan’s upcoming yet-to-be-named electric car, according to some tests, will get 367 miles per gallon. The Tesla Roadster is reported to get 135 miles per gallon. And the Chevy Volt plug-in hybrid…that depends.

If the EPA uses tests designed for electric cars to evaluate the Chevy Volt, the ratings could exceed 100 mpg. But if the government agency classifies the Volt as a hybrid and tests it as such, the EPA rating would drop to about 50 mpg. The difference could mean success or failure in the marketplace. Corporate Average Fuel Efficiency and sticker numbers for plug-in hybrids, which use gasoline and electricity in various degrees and ways depending on the specific vehicles design, have not yet been determined.

http://www.hybridcars.com/fuel-economy-num...