This is something I ran into a long while ago that I had a recent run in with again. While driving stop and go the BMW sounds like a wave pool. This was on a Z4 but I have seen this occur on other BMW models as well. There is no water in the vehicle interior but the sound of water is all around inside the cabin. It is a funny experience to be inside a BMW with this problem. I go over how to correct this if you do run into this interesting problem.
