Jay35

My comment was curiosity, nothing more. Curious to hear an AWD system described as permanently on if it actually fluctuates between AWD and FWD. That's all.

AudiPutz

Because even in dry conditions the driven front wheels rotate a bit faster than the rear ones. This makes the Haldex computer think there's a bit of slippage up front so it sends about 5% of the torque to the rear. So in normal conditions you have a 95/5 front/rear split.
The reason Audi is using it is because the Torsen quattro system was developed for longitudinally mounted engines while Haldex was developed for transversal ones (A3, TT).
As for a driving enthusiast the classic quattro (Torsen) system is better IMO. The 3.2q is my first Haldex Audi (I also drive my wife's Volvo with it) after four with Torsen (4000, V8, A4 Avant, S8). It doesn't have the "suction cup", "like on rails" feeling in sharp turns taken at high speed and it actually under steers before Haldex kicks in. I don't like that delay so I'm thinking about the Gen 2 upgrade but I'm not sure that at $1K it'll be "good enough" for me. :-) I do miss the 50/50 Torsen split.
In slippery conditions like snow I haven't notice any difference between the two systems.

Craig3Q

If you were to upgrade your Haldex controller, you would get rid of a lot of the understeer.

AJN334

That would be the torsen system ;-)