The cheap and easy answer could be that its simply loose flanging aroung your exhaust system. Part of mine got loose and used to make a rattling sound like you describe. The more expensive alternative could be that its some component(s) of your suspension. Get it put up on a lift and have a mechanic check both.
Might not be this ,..But my A6 Quattro had a slight knock when going over speed bumps..
Last night Changed Drivers side (RH) Lower Wish Bone <---Think thats what its called. Has a Large Knuckle on one side with Large Bushing,.Other side connects to Wheel with Ball Joint... Quiet now,.....Geat job...
A forum community dedicated to all Audi model owners and enthusiasts. Come join the discussion about performance, maintenance, troubleshooting, modifications, classifieds, and more for your favorite models!