I have a 2006 SL AWD. When I go over any type of bumps, I hear and feel the most awful banging noise coming from the rear area. I can't figure out what might be causing it. It's loud and very annoying. I've checked everything in the back, from the rear seats to the rear cargo area and nothing is loose. Everything is tight in the spare tire area too. If anyone else has experienced this and knows what it might be, please let me know. I would appreciate all your help. Thank you!