The X6 M is like a Doberman on a leash: if you give it any slack (a boot of the throttle, in this case), it's going to lurch forward hard, leaving you to hang on tight and go along for the ride. The mega-powered goofy-ute pulls incredibly hard with the might of its 555-hp twin-turbo V-8. After cold starts, the engine makes quite a racket, though, and sounds as if the muffler has been removed. Quite the opposite it true, though, as there are four tailpipes, the inner two of which have a cool baffle that opens on demand only. As my colleagues have mentioned, there are numerous other technological touches on display here, from the torque-vectoring differential to the crisp-shifting, paddle-operated six-speed automatic.
The X6 M, unlike the standard X6, also uses a much newer version of iDrive, so it's actually tolerable to operate.
Rusty Blackwell, Copy Editor