The Swedish Association of Green Motorists voted the "Natural Power" version of the Fiat Punto the Best Green Car of 2005. What makes that model greener than most cars is that it can operate on either compressed natural gas or regular gasoline. "The vehicle starts on gasoline, then automatically switches to natural gas. The driver can change fuel manually at any time with the touch of a button." See the technical specifications of the car and more here (I warn you: It's definitely not a racecar - but that's a good thing, right?).