Just picked up my A6 a few days ago and what a car! :-)
I've just noticed that it has an annoying exhaust vibration at the drivers side, at the tail end.
Sounds almost like a 'tinny' vibration if you understand what I mean.
Seems to be fine on the other side though.
Not the worst sound in the world and it can only be heard when you are out of the car but I guess when you know it's there, you want rid of it!
It will be a loose/broken fixing bracket. Get down n have a look....
Audi will try to sell you a whole new exhaust......
Maybe need to get right under to see it so i'll get onto that on the weekend.