Ok, so i bought this car off of my inlaws, who bought it certified with 25k on the odo. After owning it myself for 3 yrs, it now has 155k on it. It runs smoothly and effortlessly on the freeway and in and out of traffic around town. A pleasure to drive in all types of weather. Sure-footed confidence in rain, snow & ice. I put 4 studded snow tires on it each winter and have no trouble climbing any WV mountains! Amazing. I repair most things that break myself to keep repairs down to a minimum. 1 yr ago the timing chain guide rail (plastic), broke and cost me a new head! I did most of the work myself with a friend. That one set me back $1,000. A fluke I suppose...gas mileage is so-so.
Bought my Audi A6 2.8 Quattro with 121000 miles in 2014. In the last two years I've put $3000 into it and that was at small area mechanics. It's hard to find someone that knows how to fix them so take it to someone that fixes German cars! The labor is the worst because they're so hard to work on. I feel like every year I dish out more then it's worth at this point, so trying to get a new car and it won't be an Audi. I've had many leaks and the closed transmission system is a pain bc u can't add fluid manually if it's leaking. Also the pixels on the dash were going out when I bought it. Other than that the Quattro has gotten us through SEVERAL feet of snow no problem! That and the Bose system are probably the only good aspects of buying an older model with over 100k miles. Word of advice: make sure it was properly maintained at reputable dealerships and make sure u can afford the repaid costs!
I think my father summed up this car perfectly when he said this car is great... up until 80k miles. Yes, the car has exceptional awd power, fun in the winter along with luxury styling. However the designing of this car is terrible and don't let anyone ever tell you otherwise. When my 2.7t's alternator went out it took an entire day to replace. You have to take the front end off just to locate. It's ridiculous!!! the 2.7t is designed to have an extended stay at the mechanic. Over 100 sensors will cause the CEL to appear. In summary, this car is like someone else's pet; its fun to play with, it will make laugh at times but i rather not want to keep it.
I purchased my A6 4.2 from an Audi dealership, If there are any reliability issues I am going to assume they are already taken care of, the car is quick, fun to drive and is not afraid in bad weather even with 300 ponies going to the ground (thank you quattro) my best advice, see if they have service records on the car you wish to purchase, and ask them what was done to the car before they put in on the lot. The dealership I bought mine from spent about 1800 dollars in the shop correcting a few problems associated with most Audis. I have owned a lot of cars, this one is fun and a great value for a luxury sedan (thousands less than BMW or Mercedes)