BMW’s M-division has confirmed the existence of an all-wheel drive F10-series M5 test unit.Traditional fans of the blue and white propeller badge, best known for its commitment to rear-wheel drive, will feel uneasy with this latest development. BMW engineers, though, are furiously at work trying to master the intricacies of high-performance all-wheel drive systems having launched the (rather) controversial X5/6 M-SUV models back in 2009.SHOCK VALUEThe notion of BMW’s M-division engineers toying with a new M5 running power to all four wheels, courtesy of an upgraded version of the xDrive system, will no doubt upset M-car acolytes. However upsetting it may be, this design imperative does tie in with comments made by M-division research and development boss Albert Biermann.When Bierman said "there will be some all-wheel-drive surprises on M cars in future" early in April, 2011 he was not making a simple April Fool joke. In terms of shock-value, the roll-out of an all-wheel drive version of the forthcoming fifth-generation M5 – a car already eschewing BMW’s love affair with natural-aspiration – will surely grate on M-division fans a lot more than the debut of the notorious X-series M-cars did. SNOWED-IN LOGICWhy is BMW allowing its engineering resources to be deployed in the interest of developing a drivetrain system that seems diametrically opposed to the fundamental values of its M-division? Well, the simple answer is Audi - and, to a lesser extent, Jaguar which has promised an all-wheel drive XF soon.BMW is fearful it could start ceding market share to AWD rivals in its largest market – North America – where powerful rear-wheel drive performance cars are falling out of favour with customers due to their perceived lack of driveability in snowy, winter conditions. With each generation of the seminal performance sedan being more powerful (the new M5 will be good for more that 400kW), the uncomfortable truth is that not all prospective owners, very few in fact, will have driving skills commensurate to the dynamics of their BMW M5. Whatever the reasons behind BMW’s decision to push development of an all-wheel drive M5, full details are expected sometime in June with the fifth-generation M5’s public debut pencilled in for September 15, 2011.