Essentially a derivative of the X5 sport-utility vehicle, the BMW X6 flaunts a sleeker, more fluid appearance.Regardless of BMW's preferred nomenclature as a Sports Activity Coupe, the four-door X6 is not a coupe.Nor is it a true SUV.Since its debut, the X6 concept has been echoed by several premium automakers, including Mercedes-Benz and Range Rover. BMW itself markets a smaller X4 version.

Powertrains essentially duplicate those available in BMW's more upright-looking X5.A turbocharged 3.0-liter inline six-cylinder engine goes into the rear-drive X6 sDrive35i, as well as the all-wheel-drive X6 xDrive35i.Working with an 8-speed automatic transmission, the six-cylinder version performs with passion.

A twin-turbocharged 4.4-liter V8 that develops 445 horsepower and 400 pound-feet of torque goes under the hood of the X6 xDrive50i, which comes only with all-wheel drive.BMW claims 0-60 mph acceleration in 4.6 seconds, versus 5 seconds for the X6 xDrive35i.

For those who crave even more muscle, the BMW X6 M comes with a stepped-up V8 that whips up 567 horsepower and 553 pound-feet.That's sufficient to blast this comparative heavyweight to 60 mph in an even four seconds.The X6 M also gets an 8-speed automatic transmission, but with a taller first gear.Performance enhancements for the X6 M include stiffer springs, rear-axle air springs, adaptive shock absorbers, and high-performance brakes.Driving modes include a Sport+ setting that almost shuts down the stability-control system.