I am driving a fully loaded 2015 S6 Wagon as a daily driver for 8000 miles now and it is a very very good car. The interior is kind of perfect and it has lots of electronic gizmos that make travelling short or long distances easy ( night vision view and mighty automatic speed adaption for autobahn driving which basically allows you just to set a speed target and does accelerating/braking on its own, you just need to stir). There is more than enough power, my only small complain is the turbo lag could be smaller, but this is no Problem for a daily driver. I would advise to make a long test drive and see how you like it. Small note, you need to adjust the drive mode, the default is for saving fuel and does make the car feel slow.