Any BMW model bearing the M designation is bound to be immensely powerful, and this example is no different. Just like the M5 and M6 coupe, the M6 convertible is equipped with a 5.0-liter, 40-valve V10 with double-VANOS variable-valve timing that puts out 400 horsepower in normal mode or 500 ponies when a power button is activated. A seven-speed Sequential Manual Gearbox (SMG) automatic transmission delivers the good to the rear tires, which like those up front, measure 19 inches. With all 500 horsepower on tap, the 2007 BMW M6 convertible reportedly reaches 60 mph in only 4.5 seconds and tops out at an electronically-limited top speed of 155 mph, figures that are synonymous with those of the M6 coupe.