My experience of Audi is two A4's and they were absolute friday afternoon cars, always going wrong especially the electrics, never again, the same with VW, (two Golf GTIs and a Passat).
Over the many years of company car driving new cars, the best in terms of reliability were Mercedes and Citroen (XM many years ago). Worst; Audi, VW, Ford and a Rover 820 (I didn't choose this one I was allocated it, utter crap car).
Worst dealers; VW by some margin. BMW are snooty and crap service, but they at least mend the car. VW just return it unmended and then say they have done the work.
Best dealers; Nissan, Toyota and Mercedes.