TUCSON, AZ – Audi AG unveiled in Germany this week a new-generation version of its landmark quattro all-wheel-drive system engineered to impart Audi’s AWD vehicles with handling that more closely replicates that of rear-wheel-drive vehicles.

New quattro system launches with high-performance Audi RS4 in Europe.

The new quattro system – launching with the high-performance RS4 sport sedan in Europe – under normal driving conditions “biases” 60% of drive torque to the rear axle and 40% to the front. Since quattro’s inception in 1980, Audi maintained a balanced 50/50 front/rear default torque distribution that it said imparted a high level of security and dynamic stability.

But the traditional 50/50 torque split also imparts quattro-equipped Audis with an inherent and safe understeering handling character that long has been judged dynamically inferior to vehicles – primarily luxury sport sedans – whose rear wheels do 100% of the driving.

Audi engineers, anxious to achieve dynamic parity with its RWD Mercedes and BMW (and now Lexus, Infiniti and Cadillac) rivals, have reengineered the quattro system to send 60% of engine power to the rear wheels, which they say is enough to deliver RWD-like handling while retaining the stable chassis dynamics and all-weather traction ability that were quattro’s original reason for being.

Audi hallmark Torsen center differential reconfigured for rear torque bias.

And although the new quattro system debuts for the European RS4 that will not reach North America until 2006, Audi officials here for the launch of the redesigned A4 say U.S. buyers nonetheless will be some of the first to get a taste of the new, rear-biased quattro drivetrain: The ’05 Audi S4, due to hit the U.S. in April, also will be fitted with the new-generation quattro system.

Marc Trahan, Audi of America Inc. director-product management and quality, tells Ward’s the ’05 S4, a 340-hp, 4.2L V-8 equipped variant of the A4 that is a rung lower than the 420-hp RS4, will be the only U.S.-specification Audi to boast the new-generation quattro system until mid-2006, when all ’07 quattro-equipped Audis will be fitted with the new rear-biased architecture.

“The rear-bias (quattro system) fits well into our new, sporty direction (for the Audi brand),” Ulrich Hackenberg, head of concept development and body engineering for Audi AG, tells Ward’s here.

The new quattro system, though changing to the new 40/60 front/rear fixed torque bias for normal dry-road driving, still will retain the quattro design’s primary feature: the ability to apportion the optimum amount of torque between the front and rear axles when wheels lose traction.

The ability to apportion a variable amount of drive torque to either axle in reduced-traction conditions is enabled by the Torsen-design center differential, which has been the heart of the all-mechanical quattro system since Audi adopted the technology in 1987.

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