2013 BMW M6

In practical terms, the new 2013 BMW M6 Convertible is an M5 with half the doors, more of the weight, and none of the roof. It uses the same 560-horsepower, twin-turbo V-8 that, on top of delivering more power than the outgoing V-10, returns better fuel economy. The drive wheels (rear) are the same, as are the seven-speed twin-clutch transmission and the Michelin Pilot Super Sport tires.

Also similar is the "Are we really going that fast?" effect resulting from spurts of wide-open throttle. It's the product of a subdued engine note, nice damper control, and endless torque. At 4490 pounds, the M6 weighs 106 pounds more than the already portly M5, and, as you might expect, it posts slightly slower acceleration numbers as a result -- "slightly slower" though, in this case, means reaching 60 mph takes for only 3.9 seconds.  Unfortunately, reaching that acceleration requires using the same fussy and cumbersome launch control system found in the M5. The process: Turn stability control off, ensure that the transmission is in its most aggressive shift setting (S3), lightly step on the brake with your left foot, and hold the shifter forward. When the flag appears on the dash, go to wide-open throttle, and, when the revs settle, release the brake pedal.There are many problems with this process. Obviously you can't use launch control when the car is still warming up, nor can you use it multiple times in a row. The absence of a "Launch Control unavailable" warning on the dash means you never know why the car isn't entering launch control. Instead, you get frustrated, wondering if the car isn't ready, or you've done something wrong.