BMW M5 to go all-wheel-drive?

Is BMW considering an all-wheel-drive version of its new M5 sports sedan? That's the question following criticism in some quarters that the vehicle cannot get all of its epic twin turbo V8 power to the road.

On the route mapped by BMW for the international launch of the fifth generation M5 in Spain – where more than 400 journalists from around the world were invited to test the car over three weeks – the rear-drive M5 at times struggled for grip whether on older, marble-like pavement or newly laid bitumen, even while performing such basic tasks as overtaking.

At first, project manager for the M5, Maximilian Ahme, said the regular intervention of stability control was unique to Spanish roads.

“Today some roads are very slippery, I think they put olive oil on it. It’s like winter driving [in] some parts.”

However, when asked if BMW was considering an all-wheel-drive version to resolve the issue, Ahme revealed: “We are thinking about it."

"If you increase the power more and more maybe it’s better to have four-wheel-drive. But you have about 80-100kg more weight, and this on the front axle, that’s the problem. We don’t want to have this,” Ahme told motoring.com.au.

The new M5 has already put on a stack of weight; the previous V10-powered model tipped the scales at 1780kg, the new twin-turbo V8 car is 1870kg. However, Ahme revealed BMW had studied the clever, compact and lightweight all-wheel-drive system pioneered by Ferrari in the FF V12 sports car.

“We look at all our competitors, we exchange cars,” he said. “Yes of course, the technik [technology] is brilliant in Ferrari cars.”

The Ferrari all-wheel-drive system is roughly half the size and weight of a conventional AWD system. When the electronics and other ancillaries are included the total weight is just 45kg. To look at, it’s about as big as a small sports bag.

As with many other AWD systems, it saves fuel and power loss by only activating when required. The Ferrari FF is 100 per cent rear-drive – until it senses wheel slip and begins sending power to the front wheels

But that’s where the similarities with other AWD systems end. The unit that drives the front wheels gets its power and torque directly from the engine’s crankshaft. A set of gears manages the difference between engine speed and wheel speed. Two multi-plate clutch packs then apportion power to a half shaft connected to the front wheels, as required.

Uniquely, this means there is no direct mechanical connection between the front and rear axles. Instead, power to the front wheels is controlled electronically.

The FF can drive via its front wheels only – should the need arise – although not at full power. The unit driving the front wheels is restricted to no more than 30 per cent of the engine’s maximum torque at any given time.

Because of the limitations of the gear set that manages the difference between engine speed and wheel speed, the maximum vehicle velocity the system can operate at is about 200km/h.

Ferrari has patented its ground-breaking 4WD system, which it has been developing since 2004, and therefore has the rights to on-sell the technology if it so desires.

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