2007 BMW M6 Convertible

The cars from BMW's M division are virtuoso performers, built upon a rich layer of engineering ingenuity and an imaginative application of choice materials. The new M6 Convertible is no exception. Mechanically identical to its coupe counterpart, it's a gem.

The 500-horsepower V-10 reminds us that BMW builds fabulous engines; its road-holding and balanced handling suggest a special relationship to gravity; and its huge brakes yank the car's exhilarating forward motion to a quick and stable halt. But this gem has a major flaw.

The SMG transmission diminishes an otherwise exemplary driving experience. We've driven an SMG a bunch, in lots of different BMWs, and we're still not much better at shifting it smoothly than we are at delving into the dark recesses of iDrive (another misapplication of complex engineering).

Apparently, others feel the same way, as BMW has announced it'll introduce a six-speed manual to U.S.-bound M6 and M5 models in spring 2007. As a four-seat performance luxury convertible, the M6 has no peer, but with the right transmission it could be even better.