[A4] Quattro System in '99 A4

[Derek Pulvino]

Can somebody link me to a page that describes how the quattro system works in this vintage of A4?  

As I understand it, this year of the car of course uses the torsen but there is no locking differential at this point; any wheel slip that makes it's way through the torsen is counteracted by braking at a wheel?  Were they also incorporating any kind of throttle control at this time (i.e. if wheel slips, throttle is backed off) or did that not get implemented until the drive-by-wire throttle was installed?

And what's the story with the ESP?  When was usage of that system begun?  Best I know, that's not included no my vehicle.

I'm all the more curious these days as I recently had my first snow driving.  The car generally felt much more stable or maybe I'd say "dumbed down."  It was very difficult to get any wheel-spin in the snow, but tracking was good on and off the throttle and brakes.  Just trying figure out what exactly is going on where the rubber meets the road.

Derek P