I have a weird sound on a Mercedes E450 Convertible 2019. When I drive on a speed bump, even on very low speed (parkings) the back window emits a sound like something inside the door was hitting it or just things are getting back in place, like a weird knock knock. After a couple of these the sound doesn't come back, unless I open the door again and the rear window goes down to make again a little gap for the door to open.

 

I have been having the same issue on my e53 coupe. Have you resolved the issue? And if so how? Thanks!