2006 BMW Z4 M Roadster and Coupe

Interior

A 10-speaker audio system with single-disc CD and MP3 is standard, and a THX-certified audiophile system is optional as part of a Premium Package. As in all M models, the instruments are special: The speedometer expands to 180 mph and the tachometer to 9,000 rpm to reflect the M engine's high-rpm capability; an oil temperature gauge is added at the bottom of the tachometer dial, and there's a variable tachometer warning segment that adjusts the redline according to engine temperature—lowest when cold, then increasing in increments to 8,000 rpm when fully warmed up.


Other M upgrades include a wider-track front suspension and modified rear suspension with M-specific calibration, Dynamic Stability Control (DSC) with specific M logic, an M-variable differential lock, M3-type hydraulically assisted steering (vs. the standard Z4's electric power steering), large cross-drilled and ventilated 4-wheel disc brakes and 18-inch Z-rated performance tires on double-spoke M wheels. Also, because the tires are not run-flats and there's no spare, an "M Mobility System" (a container of sealant, a small compressor and a hose) is provided that BMW says can temporarily seal punctures up to about 1/4 inch across.


While the standard 3.0-liter Z4s offer 255 hp and 5.6-second 0-60 performance, these new M versions are highly motivated by an M-massaged 3.2-liter inline six boasting 75 more horses and 4.9-sec. 0-60 capability, according to BMW. This high-revving thoroughbred features BMW's Double VANOS variable valve timing on intake and exhaust, an extra-high (11.5:1) compression ratio, an individual throttle for each of its half-dozen cylinders, a selectable "Sport" setting for throttle response, high-performance cooling and lubrication, a free-flow exhaust system and more.

M Power

The M models' only transmission is a slick-shifting, lubed-for-life 6-speed manual. It drives the rear wheels through an M Variable viscous locking differential that transfers drive torque almost instantaneously to the one with the most grip. This is supplemented by Dynamic Stability Control (standard on all current BMWs), which senses wheel-speed differences and reduces engine torque and/or applies rear-wheel brakes. As in other recently introduced models, the M Coupe's DSC also keeps the brake rotors dry in rainy weather and prevents the car from rolling backwards for two seconds when starting on an uphill slope.


Following a half-day of spirited road driving, we logged some laps in a Z4 M Coupe at Wisconsin's famous Road America racetrack and came away duly impressed. As expected, its overall dynamics were outstanding. It felt light, quick and responsive and steered and cornered like a well-balanced racer, and its precise shifter found the right gear at exactly the right time. Only the DSC annoyed us at times by cutting power when accelerating out of turns. This would seldom be a problem—and could be a lifesaver—in spirited road driving.