BMW's M-cars have always thrilled drivers, but the new M6 is one of the best ever. Its 5.0-liter V10 pumps out a none-too-shabby 394 horsepower during relaxed driving, but hit the power button-an automotive first-and it will light up the rear tires with 500 horses. To squeeze out even more performance, BMW added variable valve timing and pushed the redline up to 8,250 rpm, then matched the engine to a seven-speed, paddle-operated sequential manual gearbox. It's 4.6 seconds to 60 mph, but sadly, the car is electronically governed to 155 mph. $100,000 (estimated)