I just purchased a 2001 X5 4.4i with 20" wheels. After riding with my two kids in the back seat and watching them bounce up and down when travelling on bumpy roads or bumpy interstate bridges, I am wondering if this is typical for an X5. (They thought it was fun). I had three adults in the back yesterday and they did the same thing, literally. Kinda embarrassing for me. I have the air suspension so if anyone can help, I would appreciate it. My wife's 2003 Lexus GS300 has a much smoother ride.