BMW's M6 convertible trades the coupe's sweet carbon-fiber roof for a power-folding soft top, but even that lid is somewhat unconventional. As with the standard 6-series convertible, the M6's folding top features a flared design and a vertical rear window that powers up and down independently of the roof. Putting the top down provides unfiltered exposure to the 500-hp V-10's full song (which peaks at a sky-high 7750 rpm). Regrettably, as with the M6 coupe, BMW's servo-shifted, seven-speed SMG manual is the only transmission available. Still, the combo will send the four-seat convertible from 0 to 60 mph in 4.5 seconds, according to BMW, making it essentially as quick as its hardtop sibling.