Does any have any experience with a high-frequency vibration that seems to develop as the car warms up? It is most noticeable through the steering wheel and while turning.
Thanks in advance.

'02 A6 3.0 with Triptronic 130K on the clock

 

If it happens when you apply the brakes it is your most likely brake rotors.

If it happens only when your turning or get worse when you turn have your front CV Joints inspected.

If it does it all the time check your tires for Flat Spots (broken cords) or improperly balanced and inspect you control arms.

 

Tires, control arms, tie rod ends, shocks, barke rotors or CV joints. You have to get under there and look (or have someone who knows Audis do it for you).

Good luck. Mine still vibrates after replacing all of the above....

Bob