Audis have a torsen center Diffs. The only way torque would not be split 50/50 front/rear, is if slippage occurs at one or more wheels. My A4 has traction control which applies the brakes to the wheels breaking traction.

 

awd is only when the back tires/ or front tires which every it maybe then the other set of tires kick in turnin to get the traction back, i believe thats how it works

 

The all wheel drive should send half the torque to the front and half the torque to the rear
wheels when accelerating.

 

My 01 A4 AWD kick's on at about 15 MPH before that it's just the front wheel's pulling if that help's?

 

as far as i know, theyre awd all the time...no shutting down power to any wheels under normal conditions. have a read....some interesting material in this

http://en.wikipedia.org/wiki/Quattro...rive_system%29

i actually just read/remembered that the TTs (and a3s) use the Haldex awd system, so theyre not the same as your normal torsen based awd. the haldex splits torque 35/65 under normal conditions