The rest of the car showcases BMW technology, too, just as the M5 does. The 5.0-liter V-10 engine uses double-VANOS variable valve timing, has ten individual throttle butterflies, spins up to 8250 rpm, and sustains piston speeds that are close to those of a current F1 engine. The engine makes 394 hp and 384 lb-ft of torque when you're puttering around, but you can liberate all 500 hp by pressing the power button. The engine is mated to the latest version of BMW's sequential-manual gearbox (SMG), which has no fewer than eleven modes, including a launch-control setting. The speed-sensing differential lock can transfer 100 percent of the available torque to either rear wheel. There's skid control, three-position electronic damping, and Servotronic steering with dual modes, firming up for spirited driving. There's even a head-up display that shows speed, gear selected, and a tach dial so you can keep your eyes on what's going on outside rather than glancing at the instruments-fundamental when the V-10 is roaring.

The engine is amazing. It lacks the low-down thrust of a supercharged Mercedes-Benz AMG V-8 but has an entirely different character. Thanks to a relatively flat torque curve that gives 80 percent of maximum pulling power over a 5500-rpm range, there's decent grunt from low revs, but overall it's racier and more hard-core than the Benz. The 3771-pound M6 will accelerate from 0 to 60 mph in about 4.4 seconds, reach 100 mph in less than 10 seconds, and go on to a top speed of 155 mph. Without the speed restrictor, we are told that it will hit more than 200 mph.