The X6 M steps up from the 400-hp, 4.4-liter V-8 to a twin-turbocharged version making 555 hp. Torque is rated at 500 pounds-feet. BMW says the zero to 60 mph time is 4.5 seconds. A six-speed automatic is the only transmission offered with M-tuned Drive, Sport and Manual modes, the latter of which is activated with the console shifter or aluminum steering-wheel paddles. For 2011, there are no significant changes.

In addition to revised suspension geometry, bushings and tuning, the M suspension lowers the X6 by almost a half-inch. BMW has also tweaked the stability system and xDrive all-wheel drive to maximize performance, more proactively shifting torque rearward when called for. A display on the instrument panel shows the driver how much power is going to each wheel. The brakes are also beefed up, with larger discs and calipers.

The X6 M doesn't hide its special status — especially with its huge air intakes in the front bumper for cooling the brakes, water-cooled turbo intercoolers as well as the engine. The M also features unique 20-inch wheels, front fender vents, quad tailpipes and rear diffuser. The side skirts are also body colored rather than black.