Hi guys. When I leave my 05 CC coupe at idle for more than 10 minutes parked, I begin to hear a loud rattling coming from the rear of the car. Its consistent every time. Sitting for a few minutes, its quiet. Then after a period of time it start making loud noises, especially if its in the garage like something loose and clanking. Its not coming from the exhaust pipes. The dealership told me that is normal for these types of cars. Does everyone's coupe do this or just something my dealership didn't want to look into?