Gone.

Originally Posted by JARblue

You say doubtful, but then you specifically refer to an apparently known issue where the cam follower destroys your engine

Would you trust that the previous owner had this done at 50K miles, especially if it's not a standard maintenance item? He said the car has 90K miles on it, so ....

You obviously know more about Audis than me. I just know their interior is very nice (understatement) and when they break down as they get on in miles, it's often serious and outrageously expensive. Hopefully you have provided him with some good, relevant information that will keep his Audi running well for the time being