The Smart Electric Drive, a plug-in version of the Smart ForTwo, tops this year's Greenest Cars list assembled by the American Council for an Energy-Efficient Economy (ACEEE), a non-profit group that promotes energy saving measures. The all-electric two-seater goes 68 miles on a full charge, which is plenty for city driving. It gets 107 miles per "gallon equivalent" of electricity. That's a measure of how far a car goes on the same amount of energy as that contained in one gallon of gasoline.
