One problem related to suspension noise has been reported for the 2000 Audi S4. The most recently reported issues are listed below.
Thunking noise in front suspension for last two years when I get on the gas or on the brakes. Two separate dealers took the car for a road test and said it was fine. It has gotten progressively louder and more noticeable. I am worried that this could be leading up to a failure of the suspension or steering.