The later part of 2009 will see the introduction of AWD powertrains versions of BMW’s 7-Series, with the first models likely appearing after a debut at the Frankfurt Motor Show in September as 2010 models. The change is, for many, long overdue as the German competition has long offered AWD for their flagship vehicles.

AWD variants of the 7-Series will once again carry BMW’s xDrive tag and will initially be available only in the 407hp (303kW) 750i. Other models had been rumored to follow soon after, but the latest reports indicate only the 750i will have the option at all. There are not yet any plans for an AWD diesel 7-Series.

The 7-Series AWD features a high-tech torque distribution system, which sends 40% of the motive force to the front wheels and 60% to the rear when traveling in a straight line. But when the twisties start, up to 80% of drive is sent to the rear axle to maximize driving dynamics, with the percentage dependent upon steering angle, reports Auto Motor & Sport.

Another new feature will be the addition of an electronic ‘Hill-Descent’ control – the first for a luxury AWD saloon. The cars will also have slightly taller ride-heights and special underbody protection, reports Automotive News Europe.

In Europe, the AWD option will add roughly €2,500 ($3,500) to €2,800 ($4,000) to the sticker price of the 7-Series, as well as an additional 110lb (50kg) onto its curb weight. Initial testing has shown that this extra weight will increase fuel-consumption over the standard RWD models by 1-2mpg (.2-.4L/100km).