With the intro of the BMW X5 M and X6 M at the New York auto show, BMW is giving in to competition from the Porsche Cayenne GTS and the Mercedes-Benz ML65 AMG. In more certain times, the X5/6 Ms would be surefire profit-makers. Instead of the M5's 500-horse, 5.0L V-10, the X5/6 M are powered by a new, 555-hp version of the 4.4L twin-turbo V-8, this one featuring a new exhaust manifold set in the engine's vee. The manifold has one turbo inlet for every two cylinders (normally, it's one inlet per turbo scroll) and swaps out cylinders to get a pulse every 90 degrees. The two Garrett twin-scroll turbos work both sides of the vee, not one per bank. The new M twin-turbo V-8's max engine speed is 6800 rpm (with turbos spooling to about 16,000 rpm at maximum turbo boost) and the engine produces a heady 502 pound-feet of torque from 1800 rpm on. BMW claims both vehicles will sprint to 60 mph in 4.5 sec.

The X5/6 M set another BMW precedent, as the first M models with an automatic transmission. The X5/6 M's "sport" mode speeds up shifting among the six gears, and the "M" mode speeds them up even further. Click on the X5/6 M's M mode and all-wheel-drive bias shifts heavily to the rear wheels, making them great drift competition candidates, BMW says. The rear bias is well past 20/80, although BMW says it's not pure rear drive. Both the X5 and X6 M go on sale late this year.