How is it dying?
It has 130k on the clock from a previous life, but I have spent the past 5 yrs primarily driving it in short journeys.
The garage tells me that the rear suspension will go one day and that is a main dealer job.
I had a brake problem recently and topped up the leaking resevoir with brake fluid (seemed logical) - unfortunately the leaking reservoir was the steering one, which also serves the brakes - it hates brake fluid and I may have damaged the steering rack.
At teh end of the day the S6 was a bit tuned up estate car (0-60 in 6.7 I think) and racehorses don't tend to live as long as cart horses do.
I still think an A6 is a good care IMHO