By Matt Vella

Green Today—Greener Tomorrow?

In recent years, automakers have rushed to market with highly efficient engines and advanced gas-electric hybrids, even as they place high-risk bets on which technologies might prevail in the future. Here, from green to greenest, are today's most environmentally friendly cars, according to the American Council for an Energy-Efficient Economy (ACEEE). The ACEEE, a Washington (D.C.)-based nonprofit, rates currently available vehicles on a green scale of zero to 100 according to metrics such as emissions and fuel economy. Also on our list: advanced concept and potential future vehicles that might show up on the ACEEE's list in the future.