You'd never suspect the X5 M is powered by a 555-hp V-8 if you were simply riding along running errands, because it behaves like any luxury crossover would in that situation. Acceleration from a stop is smooth, without any of the noise that often accompanies high-performance engines. Stops are just as ordinary, as the brakes — which feature 15.6-inch front discs gripped by four-piston fixed calipers and 15.2-inch rear discs with single-piston floating calipers — aren't grabby in the least.

You start to get a glimpse of this crossover's performance potential on the highway, where you soon realize that interstate speed limits are painfully slow when you have so much power available at just a prod of the gas pedal. Conversations about vehicles that need to be driven on a racetrack to be fully experienced are usually limited to sports cars, but the X5 M falls into this category, too. You'll pay for this performance at the gas pump, as the X5 M gets an EPA-estimated 12/17 mpg city/highway and, not surprisingly, uses premium gas.

I was particularly impressed with the clutchless-manual mode incorporated into the X5 M's six-speed automatic transmission. Nudging the gear selector forward or backward results in a quick downshift or upshift. The system's swift response makes it more engaging than most, which tend to be slow to react. A manual transmission isn't offered.

The X5 M's exhaust note is a little odd. It doesn't have the typical rumble of a V-8, but instead has the sound of a high-revving V-10. That's explained by its unique exhaust manifold, which features four equal-length runners connecting pairs of cylinders on separate banks.