[JakeG]

The older quattros are fully mechanical with a mechanical torque
differential between the front and rear. If I remember it, it was
revolutionary when it first came out and took the rallying world by
storm.. especially the souped up Audi80 quattros (which was banned later
on).

Shouldn't be much of a problem as far as maintenance's concerned except
for oil change and some of the couplings may wear.

The newer quattros have some form of intervention to make it work with
brakeforce distribution systems for traction control, so may be a bit more
complex.