Hello from newbie, I bought an older 2013 model a6 , I have to agree that fuel consumption is much poorer than I expected but I do like the car.
Audi dealer repairs are very expensive over £200 for rear pads to be fitted !
Also a couple of niggling electrical issues like heated mirror not working, passengers door not unlocking when key fob pressed etc , fan still running a long time after car has stopped....but might have to live with these faults if I can't find a good internet site that sells used parts.