I chose the A6 against Merc E-class and BMW 5-series, just because I wanted to try something different, and this vehicle seemed promising when I visited the showroom. It offers fantastic grip on the road, and I have driven it at 155 mph frequently, without being worried. All the electronics offered in the car are also very useful and good. I never experienced any error in the car as yet (after using it for over a year). I unfortunately didn't get to buy a Quattro. Therefore, i am not much happy with the FWD of this car as it tends to slip a lot during acceleration. Incase if you are planning to buy the A6, then please go for the Quattro (AWD). It literally stands out.
Interior, Audio system, User-friendly controls of Navigation and others, solid grip over the road.