Hi Paul, having wracked up 870,000 miles between three of my last cabs [Fords] I can honestly say that there are a lot of people out there that actually know what they are looking at, I actually got a good return on all three of my cars despite starship milage purly because I had replaced all the appropriate parts on them, clutch, timing belt, EGR valves and sensors at their due times and had the bills for those parts as I fitted most of them myself which took a lot of garage labour out of the equation, a sort of potted personal service history.
When I was researching the A6 as a cab I had looked at a few of them with 100,000 plus miles on them and nearly bought one of them but when I got there to view the car it was an automatic not a manual as advertised so I had to decline as where I live is lots of hills which tend to kill auto boxes in short order when the car is used as a cab, the main niggles for any potential buyer are switches that don't work, dash lights that stay on, and most of all tatty or badly worn trim/paint work.
Your car is still a baby in the world of informed diesel owners, my car is close to 90k and I have no intention of getting rid as I have another four years licence life and possibly another 200k to do before its decommissioning, and I will bet someone will still want it.
Regards Steve.