According to Motor Authority, Audi has developed a new differential that will find its way into all its Quattro-equipped vehicles next year. The new diff quells Audi's inherent understeer by shuffling torque between the rear wheels, thus improving overall road-holding and lending itself to more sporty (read: rear-wheel drive bias) driving dynamics.
The system, which sends 60-percent of torque to the rear wheels, will sense a loss of traction in less than 100 milliseconds and then send an appropriate amount of power to each individual wheel. Users will have the ability to select between three different preset modes, including "auto," "comfort" and "dynamic," the latter of which provides more competent handling at the expense of ride comfort.
Source: http://news.euro-truck.biz/autoblog/quattro-times-two-audi-develops-new-sport-differential/