I had this Audi 100 as a company car and I was a bit miffed that it wasn't a BMW or a Merc but I was wrong to think like that. The Audi 100 blows Beamers and Mercs out of the water in my opinion and it doesn't have their reputation, either. Which in the case of BMWs is that they're for morons and in the case of Mercs is that they're for snobs.
My Audi 100 ran up over 150,000 miles by the time I'd finished with it and ran perfectly for every one of these. It had the feel of a real luxury car with proper leather upholstery and a really nice looking dash. It also felt like it could really go if I wanted it to but I always drove it very sensibly of course.
I am now looking to buy one of these beauties for my own but they don't come cheap. My advice if you are looking for one is try and get one that has been owned by few people and very sensible people! It must be treated with respect.
These days people seem to sort of accept that their car will be scrap before its 10th birthday. I'm not normally a nostalgic person (I've even got an ipod!) but honestly I do think the golden age of cars has passed. Our Audi 100 still feels almost as tight as it was when we bought it about 20 years ago. There are plenty of jokes about this with our 20 year old daughter.
Anyway apart from the normal sort of repairs that need doing (i.e. brakes, exhaust, tyres, wipers, battery etc - even those quite rarely) it's had nothing need doing. Actually there was a small electrical fault about ten years ago but that was patched up reasonably cheaply.
Driving wise our Audi 100 is a pleasure. Comfort is superb. The seats are ever so slightly creaky these days but the original leather is still doing fine, only minimal cracking around the edges.
The gear changes are still smooth and predictable, no nasty surprises or notches. I suspect the gearbox may be the thing that kills it in the end, but that's only based on what I see from other cars. The 100 hasn't shown any major signs of ageing.
The down side these days is the fuel economy, and that's what may move me on to a lighter more efficient car. These days I'm averaging around 26 or so miles per gallon. It also leaks a little bit of oil, but then it is currently at 169 thousand miles! See what I mean about reliability and longevity? Careful driving pays!