With five liters of displacement, continuously, or "steplessly," variable timing on 40 valves, and electronically controlled throttle bodies feeding each cylinder individually, there's a lot of precise hardware to get working in tandem, yet response is immediate and the M5's V10 pulls to beyond 8,000rpm.
We thought that 8,000rpm was an impressive redline for the two-liter fours in the Acura RSX Type-S and Honda Civic Si; in this car it borders on astounding. A very cool touch is the variable redline indicator, which moves around the outside rim of the tachometer, starting at about 6,500rpm when the engine is dead cold and moving to its fully ready position around 8,000rpm once the engine warms up.
The single biggest control difference between the M5 and any other 5-series is a very small button among the other steering-wheel controls, called the M-Drive toggle. M-Drive is a catch-all mode representing the custom settings of six other systems: the SMG, electronic damping control, dynamic stability control, engine power mode, active bolstering, and the heads-up display (the last two if applicable).
In practice, all this translates to a means of instantly switching into hooligan mode and back to normal at the press of a button, and we loved it. iDrive itself might benefit from more control logic of this type. We know the point is to make everything controllable through one knob, but the star-symbol button on the steering wheel below the M-Drive button can be customized to perform one iDrive task, and a couple other buttons like this would be nice.
There is simply power and torque available everywhere up and down the rev range, enough to overwhelm the tires in the first three gears if you're daring enough to disable the dynamic stability control. And of course, you are, because this is the only way to get the transmission into Sport mode 6 for the quickest shifts. With this mode selected, the electronic damping set to Sport, and the engine in P500 Sport mode where it produces 500 horsepower and extra-quick throttle response, the M5 assumes its purest form and the results are breathtaking.
Full throttle shifts are lightning-quick with no chassis disruption, and SMG earns its keep. Downshifts are accompanied by an attention-getting throttle blip, which either amuses or impresses most people when rolling to a city stop but definitely helps maintain stability and avoid any unsettling wheel spin in fast midcorner changes. With seven forward gears to choose from (an industry first for a clutch-shifted production-car transmission), so many shift programs available, and unflappable grip at any reasonable speed, getting to know the M5 is a pleasure indeed.
For more sedate driving, however, the M-Drive button is pressed again, and the standard P400 (400 horsepower) engine setting is reengaged along with the other dynamic settings in their prior places. In slower driving and finesse maneuvers such as parking and hill starts, SMG can become a nuisance if the driver isn't used to it (and yes, sometimes even if the driver is). The expectation is that putting the transmission into Drive mode at the least sporty setting will make it behave like a normal automatic, but instead, shifts are prolonged and very noticeable at anything but the lightest throttle inputs, and booting the throttle at the wrong time can produce a seriously unpleasant kick in the back.
We found that the smoothest around-town driving was realized with the transmission in a midrange mode (it automatically resets to mode 3 of the 5 normal modes each time the car is started), and that shifts can be smoothed out by using the throttle as if driving a conventional manual, that is, letting off briefly while declutching happens and encouraging shifts this way. Parking takes some practice, as it can feel frustrating to goose the accelerator and wonder if your electronic friend is going to slip the clutch a little at the right time. Concrete walls and curbs loom large when still learning to feather the throttle to good effect. Hill starts are much simpler, as a depression of the left-hand shifter paddle will automatically hold the brakes on an incline for about a second before the car begins to roll backward--plenty of time to move onto the throttle and get underway. This worked fine on some steep San Francisco streets, although maintaining uphill momentum once underway was a skill we never quite mastered. A quick flick into Sport (sequential) mode would solve this, of course.
Braking is similarly impressive, with the standard 19-inch wheels providing room for four cross-drilled and vacuum-ventilated discs with ABS. Fuel gets consumed about as quickly as expected, with the trip computer reporting between 12mpg and 13mpg during our week's driving, against the EPA estimates of 12mpg in the city and 18mpg highway. Your $94,965 also therefore includes a (deep breath) $3,700 gas guzzler tax, so you might as well enjoy it, right? BMW provides the usual array of standard safety features to protect the occupants in the event of a mishap. No government crash-test ratings are available for the M5. Front dual-stage dual-threshold "smart" airbags with passenger detection are standard, as are door-mounted front side airbags and a front and rear head-protection system. An interlocking door anchoring system provides extra protection against side impacts. In a serious impact, major electrical components are disconnected from the battery, the hazard and interior lights are activated, and the doors are unlocked.
Park-distance control is standard, showing BMW's usual overhead pictogram of the car with auditory warnings and glowing onscreen zones indicating the general position of objects behind. With the navigation system standard on the M5, BMW could also pair the monitor with a real rear-facing camera, but this system is mostly effective and can be configured a bit with iDrive or switched off completely with a dashboard button.
Dynamic stability control, an all-season traction system and a variable differential lock improve handling and assure grip in bad weather conditions. Antilock brakes are standard, with adaptive brake lights that light up more brightly under sudden heavy braking. Adaptive autoleveling headlights and rain-sensing wipers, which impressed us in our test of the 550i, are also standard. A tire-pressure monitoring system alerts the driver to drops in psi at each corner and is calibrated via iDrive.
BMW offers its usual four-year/50,000 mile warranty on the 2006 M5, extendable by original owners to six years/100,000 miles for mechanical breakdown coverage. Also included for four years or 50,000 miles is all scheduled maintenance and replacement of wear items, though presumably not tires. Rust-through coverage is for 12 years.