At my S40 there is a lot of polter on the roof or on the roof of the car. At first I thought that I would have liked something on the roof, but it comes regularly at least 1x per ride. Mostly after about 10 minutes the first time. I assume that there is pressure somewhere (heaven / roof), which triggers some such effect ?! Had a half-dead Opel Vectra on loan years ago, the roof on the AB barked out again, that sounded so similar (of course much louder). Does anyone have an idea ??! Greetings $id