I've owned this car for a year now and overall I am happy with the car. The A6 is a pure joy to drive. It is very quiet at highway speeds, is comfortable for long trips, there's lots of room in the back seat for adults, and the trunk is enormous. Parts and online forums are readily available for DIY work. I've had one major problem: the transmission was repaired at 50,000. It took Audi 2 months to fix the car which is just too long. CV boots seem to be a regular repair item for Audi in general. I replaced one at 48k. Other than those two repairs the car has been problem-free. However, I recommend that if you buy an Audi then get one that is CPO or purchase an extended warranty. Check out your local dealer's reputation as they can make or break your ownership experience.
Exterior styling, Bose stereo system, interior build quality (leather and wood), big trunk, rear seats fold down for versatility, 22 mpg (city).