There hasn't been a successful start-up car company in the U.S. since, oh, Ford. But more than a few entrepreneurs believe that with the auto industry on the brink of a technological revolution, now is the time for new players with radical ideas. Michael Marks founded Tesla with the plan of creating an electric car that doesn't sacrifice performance for fuel economy — and by all accounts, the red-hot Roadster succeeds. Not only does the Tesla accelerate from 0-60 in four seconds, its battery has a range of 245 miles, making it six times as efficient as the best sports car on the market. But if you want one, you better get in line just as quickly — there's already a waiting list, and the first production models won't be available until 2008.