The 6 Series revives a tradition of a big BMW coupe, the last of which ended with the demise of the 8 Series in the mid-1990s. The new 6 Series shares a platform with the recently redesigned 5 Series, including the cumbersome iDrive control system. The standard engine is the smooth and punchy 4.4-liter V8 that's also found in the 545i and 745i sedans, thus the designation of 645Ci. A soft-top convertible version is available, defying a trend toward folding metal tops. A limited-production, high-performance V10-powered M6 is new.