As my wife and I were driving our new X5 home we opened the sunroof, turned-up the radio and were loving it! After about five minutes we looked at each other and were getting a vibration feel, started to get a headache, and had to pop our ears? When we rolled down one of the other windows the effect went away. I spoke to a someone who has an X5 and they said that too happens in theirs - because the car is built so tight. Does this make sense? Thanks a lot.