My wife owned a high mileage Audi 5000Q about ten years ago. I am a decent mechanic but the car was a maintenance money pit; every month some other costly thing broke and needed to be replaced. The power steering rack leaked slightly when she bought it, and it leaked a whole lot more six months later. The rack needed to be replaced. In order to remove the rack the engine would have had to be removed. Sort story, that was the last straw. She sold the car at a loss and was happy to do so.
I think that new Audis are great cars; older ones not so much. Consumer Reports until recently did not recommend the purchase of ANY Audi.