I rather think there's a sentence in the first post which makes all the talk of dealer warranty irrelevant.
"The car was owned by the son of the garage owner who took me out. "
I suspect when it all comes down, this has been a private sale between the garage owners son and the OP, so any talk of dealer warranty will be pointless. I've seen this before by a well known (at the time) tuning company who sold someone a Passat. They were careful enough to cover any possibility of comeback by running it as a private sale from the owners wife to the individual.