Has any body else had this?  When I'm driving over rough pavement, brick and cobble stone type surfaces there is a muffled rattle coming from the right rear of the car that continues for a moment after getting back onto a smooth surface.  The dealer has been no help.  Also this vehicle has had front rotors replaced twice, a rear main seal replaced twice, a wheel bearing replaced, an engine mount replaced, cam cover seals replaced, and a transmission multi-function switch replaced.  Other than those problems I love it.  The car is a 2001 A6 FWD.

I had the same sort of problem once, so I took it to the audi dealership in westchester, NY.  They told me it was tic-tacs in my console!!!

Turns out it was my rear caliper - the bolts that held it in place fell off.  Make sure that the bolts on your rear calipers are on.