The comfort access option allows entry and engine-starting with the key pocketed. Numerous other lighting and central locking options are controllable with iDrive, as is the automatic air recirculation system. Climate control requires some iDrive use for setting airflow, but there are dedicated controls for fan speed and temperature for both front seating positions. The 2006 BMW M6 features one of the most potent production-car engines currently available. Thanks to individual throttle bodies for each of the 10 cylinders, an oversquare bore-to-stroke ratio and steplessly variable valve-timing, the 5-liter unit revs with amazing ease. Power is always available, and mashing the throttle to hear the ensuing bark and crescendo from the four big exhaust outlets becomes addictive. As we noted in our M5 review, the production of 100 horsepower-per-liter of displacement without forced induction is impressive in 2-liter engines such as the VTEC four-cylinder engines found in Honda and Acura models; the same relative output, along with an 8,000rpm redline in a 5-liter V10 is almost magical.
Acceleration is rated by BMW at 4.5 seconds from 0 to 60mph, the same as for the M5. The M6 is about 100 pounds lighter than the M5, thanks mainly to the carbon-fiber roof panel, a first for a production car, and this--along with the resultant lower center of gravity--makes the M6 feel slightly more responsive.
The main obstacle facing an eager M5 or M6 driver is the unorthodox SMG transmission. Novices must endure lots of hesitant starts and head-bobbing low-speed shifts, but with practice things can be smoothed out for creeping around town. SMG really shines when the most is being asked of it, and of course pushing the M6 this hard on public roads draws attention. Our test car's Interlagos Blue Metallic paint turned heads everywhere we went, and this color is potentially license-threatening when driving the M6 at anywhere approaching its potential.
Among the buttons on the M6's thick M-stitched steering wheel is the M-Drive toggle, which instantly configures the electronic damping control, transmission and engine modes, dynamic stability control, and heads-up display to the driver's preset settings. The purest modes for the engine (P500 Sport, giving 500 horsepower and the crispest throttle response) and transmission (Sport 6 for ultrafast upshifts) are available only with M-Drive activated. Stability control can be completely defeated for sideways shenanigans, but is probably best left in M mode, where some wheel spin is allowed. Speed-sensitive variable-assist steering with a special M-Dynamic mode provides excellent feel and feedback over all road conditions.
Despite our gradual embrace of SMG in the M5 and then the M6, we are relieved to hear that BMW plans to offer a standard six-speed manual with the 2007 M5. Under full throttle, SMG shifts faster and cleaner than most people can match and blips the throttle automatically for perfectly rev-matched downshifts every time. But its foibles can be frustrating under normal conditions, and many buyers will opt for the direct feel and familiarity of the six-speed. Hopefully, the M6 will also get the choice--perhaps when the recently announced convertible debuts for the 2008 model year.
While EPA fuel economy ratings are the same for both the M5 and M6 at 12mpg in the city and 18mpg highway, the M6's slightly better combined rating saves it $700 in gas-guzzler tax over the M5. The 2006 BMW M6 has yet to be crash-test rated by the NHTSA, but safety features abound. Park Distance Control is standard, and while no rear view camera option is available, it is effective enough with its overhead view of the car, color-coded intrusion zones, and progressive proximity audio warnings. Adaptive headlights are also standard on the xenon beams, as is dynamic automatic leveling.
Tire-pressure monitoring is standard, as expected with this level of performance. The rain-sensing wipers weren't called for during our week with the car, but the system worked very well in the 550i we tested previously.
Dual-stage, dual-threshold "smart" airbags protect both front occupants, with door-mounted side-impact bags also standard. A head protection system covers both front and rear passengers, and interlocking door anchors improve crashworthiness in side impacts. Serious collisions trigger the disconnection of alternator, fuel pump, and starter from the battery and also unlock the doors and turn on the hazard and interior lights.
BMW's standard new-vehicle warranty is good for 4 years or 50,000 miles, with all scheduled maintenance included. Roadside assistance is also provided during this period. Rust-through protection covers the body for a period of 12 years.