I had an Audi and a VW V6 (same exact engine as Audi), and both had hugely expensive engine repairs that were truly design issues, and both had the check-engine light on more than off.
For the 2008 Audi A4, even though the check-engine light was an on-going issue from day one (9K miles actually), after the 50K warranty expired, the dealer charged me $1,600 when it came on, and the next day it was on again and they charged me again. I said you owe me for the last one since that obviously wasn't the issues. The service manager responded "that's what the computer said it was." Then there was the time at 19K when the whole car shut down on an 8-lane highway in heavy traffic. The dealer said it was "just a random computer failure."
On the 1999 V6 VW, the rear cam seals blew out because the PCV (which they recommend never to change, and the dealer will not change it because of that even if you ask them to). I had to rent a car for two weeks because the PCVs were back ordered. Funny how they were back ordered when they don't change them. Maybe they had an issue they don't want to admit. Mine was out of warranty, but I had two friends with the same issue. And even though theirs were in warranty, VW wouldn't cover it because they didn't get their oil changed at the dealer. I found this especially hilarious, because the times I did have mine done at the dealer, they gave it back one quart low. I called the service manager and he said, "maybe the mechanic thought it was a 4 cylinder." Of course it said V6 in big silver characters right on the plastic engine cover.
Fast forward to this year, my co-worker bought a new GTI last year, and the entire engine needed to be replace for $12K. Even though it was under warranty, VW wouldn't cover for the same, you guessed it, didn't have the oil changed at the dealer.
I could go on for hours, never mind the recent cheating the codes on the diesels.
I would not buy another Audi (VW) product no matter what!