Just found your Audi forum and probably should have long ago. I am now into my 6th audi-an A8, and just reluctanly parted with a 1991 20 valve Avant with 230, 000K and running very strong. Before that an 1988 5000 TQ Avant with 275,000K.
I am getting very used to my 1998 A8, as I travel a lot. I miss the 5 speed and more "serious" purpose of the 20 valve, but really think I made a good selection. Always open to any suggestions for both maintaining it and enjoying it. I don't think I can ever go without an Audi again.