Sorry to contradict, but the Subaru WRX STi w/ its center active diff and two mechanical front and rear diffs is more superior if you are looking to put all the power to the road.Originally Posted by D0WNxSH1FTSo the torsen diff is only at the center and can only distribute 100% of the tq to either the front or rear axles. Between the left and right wheels, the brakes are used to stop the wheel from slipping allowing torque to reach the wheel that isn't (usually the outside rear wheel). The Subaru Sti AWD System and Mitsubishi ACD (w/ or w/o AYC) is far superior for putting the torque to the wheels if called upon. You certainly don't want the brakes being applied when you want all the power spinning the wheels (for drifting, gravel cornering, etc...)And to ensure tire traction even on wet pavement, A4 is also available with Audi's Quattro all-wheel-drive (AWD) system that's always engaged.
The smart device, using a torsion-sensing center differential, automatically shifts the majority of all engine torque to whichever wheels, front or rear, attain the best bite of traction on slick pavement.
Another mechanism applies electronic locking to front and rear differentials in a process that can sense and block an individual wheel from spinning, then redistribute the driving torque from one side of the axle to the other.
Don't believe the hype from Audi, BMW, VW, Volvo, etc... Three viscous, torsen, mechanical or Active diffs are better than a single one + ABS.
NOTE: Incidentally the Acura SH-AWD is the best system to come to market with 3 active diffs to send the torque to exactly the one wheel that needs it (outside rear to fight understeer). Its a shame the car (Acura RL) isn't lighter w/ a more powerful engine to capitalize on Honda's newest tech.