2006 BMW M5

Mark Bramley
2006 BMW M5
Front Interior View

Gerd Richter, technical director of the M division, describes the decision not to use composite brake discs: "Ceramic discs are lighter, but they cannot absorb as much heat as cast-iron rotors. This diverts the temperature stress to the calipers, which subsequently need to go up in size and weight, so you lose some of the initial advantage while at the same time further increasing the cost deficit." Be that as it may, the ventilated and cross-drilled metal discs fitted to the new M5 are beyond reproach. Straddled by massive Teves two-piston calipers, they combine bite and stamina, low noise and smooth response. Even when they're pushed to the limit, all one notices is a whiff of parfum de pad and a pit-stop-like cloud of dark dust rising from the front wheels as the vehicle comes to a halt.

You will be pleased to hear that wear can be easily induced at the other end of the car, too. As soon as DSC takes a rest, the bespoke Z-rated nineteen-inch tires work overtime. In the dry, there is full-throttle wheel spin in first (unlimited), second (plenty), and third gear (enough to change the color of your hair in the middle of a fast bend). The second-generation Continental SportContacts developed especially for this car blend narrow slip angles-vital for precise turn-in-with a creamy breakaway.

Full Engine View

The aluminum rear suspension has been extensively modified for the M5. Most of the rubber mounts were replaced with stiffer bushings, the lightweight driveshafts are now hollow and stiffer, and the geometry was recalibrated to match the substantial increase in power and torque. Like the M3, this bigger brother is fitted with the progressive M limited-slip differential that automatically diverts the lion's share of torque to the wheel that can make the most of it. In extreme conditions, the locking ratio increases to 100 percent. The engine torque is relayed to the M differential via a new seven-speed sequential transmission that was developed with Getrag. Richter explains why BMW stuck with the sequential manual gearbox rather than a twin-clutch unit: "True, the dual-clutch system has a smoother automatic mode, and it performs seamless upshifts. For a 7-series, this may be the way to go. But an M car should always combine efficiency with emotion. That's why there are six shift speeds to choose from, from velvet glove to iron fist. That's why we cut the torque into seven slices. That's why we added special features like a hill holder, a designated drive program for steep climbs and descents, and a downshift assistant, which briefly dips the clutch to avoid destabilizing wheel spin."

Like every iteration of the SMG theme, this latest version eclipses its predecessors. But, also like the others, even the seven-speeder falls short in some departments. The most controversial issue concerns the shift paddles, which are attached to the steering wheel, not the steering column. This may be an advantage on racetracks such as the Nrburgring Nordschleife, where BMW does a lot of its testing, but it doesn't work so well in real life, where you come across 90-degree corners and hairpin bends. As soon as you need to change your grip on the wheel, you no longer know where you are in relation to the silver flaps marked minus and plus. You can always rely on the shift lever, however, provided you remember to pull it back for downshifts and push it forward for upshifts. After two days and more than 300 miles in the new M5, we would vote for a pair of large fixed actuators. We would also encourage Richter and his team to further hone the automatic mode. This is the first M car that drives reasonably smoothly in the auto mode-but only as long as you stick to a rhythm that's familiar to the SMG electronic brain. Unfortunately, the chips still struggle to cope with maneuvers such as sudden kickdowns or aborted overtaking at-tempts. For best results, choose a medium shift speed. Slow is valium, fast is jerky and abrupt.

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