Hi , I had a rearguard on my last A6 avant , it was ok , it is attached with double sided tape which sticks ok but I used additional tape to ensure it didn't come loose. Ive got an S4 avant coming in a couple of weeks and on this car I'm going for the Venture Shield film on the front of the car against stone chips and they also do the rear bumper so if that is ok I wont bother with the rear guard . Why don't Audi fit something on as standard even Peugeot do !