yes, I have (2) 2000 A8's with the exact same problem/ Do you have a Vag-com? If so, I have a partial solution. There's an adaption sequence you can run which will last a little while and make a HUGE difference. The computer resets itself so it only lasts a couple of weeks/few hundred miles.
I don't have it in front of me so please email me and I'll send to you and post. I do it every few weeks on my cars, only takes a minute.
Bob
rdunne14@comcast.net
P.S. - don't know if this will work for pre=facelift cars. This is NOT the notorious thumping issue that the pre facelift cars have.