newfinish

* "quattro IV" - permanent all-wheel drive system, includes TORSEN torque sensing center differential; front and rear electronic differential locks (EDL) (4.2 model only)
* Anti-lock brake system (ABS 5.3) with electronic differential lock (EDL) and electronic rear brake pressure regulation.

never felt the locking difs last winter i got stuck because the wheels where hardly turning,is there a vacuum that locks these difs or it was an option to have those locking difs?

ryoung

... "lock" the differential and stop a spinning wheel.

You could manually override the diff lock by simply lightly applying the brake pedal (if Audi's computer wouldn't cut the throttle). Early HUMVEE's use Torsen front and rear differentials and no diff lock. When climbing steep slippery hills, the approved procedure was to apply as much brake as necessary to transfer torque to the wheel with traction. It's amazing how well (and simply) this works.

<img src="http://www.dueckgm.com/marine/images/fun/hummer/Hummer-Humvee-800.jpg">