Truly special car
I have owned a number of Audi cars and this is by far the best I have driven. It is very quiet and smooth and the acceleration is the best aspect of the car. I purchased it used with low mileage and it is a great value. This car will be memorable.
Perfect balance of performance, comfort and luxury
You can really have fun with this car. Drive on rails, takes sharp turns at high speed effortlessly. The acceleration can be mind numbing, especially with Launch Control. Mine was well equipped (e.g. perf package, massage and ventilated seats, etc.) so it made it even more enjoyable. It's quiet and comfy when you want it to, like driving the family around, and you can wake up the beast for some personal fun on the track, empty canyon roads or highway ramps.
Disappointing test drive
I really wanted to like the S6. C&D magazine gave it a win against the F10 M5 and E65. I drove it twice, extensively, because I really wanted to like it. Pros: The engine and transmission allow for extremely quick acceleration. It made me smile every time I put my foot down. It just GOES, extremely effortless acceleration. The interior is very well made. The displays are clear and beautiful. Cons: The car is not fun to drive unless you only care about acceleration. It is solid, quiet, stable, it can take high speed turns well, but the steering is so lifeless. You can change it to a nicely firm "sport" setting, but there is still no steering feel. It's like a better Lexus LS than Lexus could muster. I gave my $80k to the Porsche dealer next door.