Formula M

It might seem impossible to improve on BMW’s 3 or 5 series sedans. Yet the impossible is routine for BMW’s technicians, who’ve been upgrading their production cars since 1978 to attain BMW’s “M” standard. For the first time in 2007, they’ll create four such models: the M3, M6, Z4 M-Class, and the superb M5.

The M5’s five-liter V10 engine is a derivative of last year’s BMW Formula 1 racing engine, tuned to provide a smooth-revving—but restrained—400 horsepower. Release the computer-controlled engine restraints by pushing the “power” button on the console, and the M5’s true character emerges: a full 500 horsepower, plus quickened steering response and stiffer suspension to control the power increase.

The M5 has a seven-speed sequential manual gearbox. Leave it in drive for automatic transmission, or move the lever to the side to enable paddles on the steering wheel for manual upshifting with the right thumb, downshifting with the left. To shift smoothly, you’ll need to modulate the gas pedal, run the revs up, let off the gas, hit the thumb switch, then step on the gas again to realize you’re up a gear. When decelerating, the car revs itself slightly to synch up the engine speed for perfect downshifts. Console switches adjust how high the engine revs before upshifts, shut off traction control, and diminish the stability control just a bit—enough to allow you to hang out the rear end for a little fun in hard cornering, but not enough to cause loss of control.