My E430 has the same rattle, but I don't think it is the sunshade. I have ridden in the back seat while another driver traverses railroad tracks and I am convinced that it is the headliner rattling against the rear of the sunroof frame (which is just above the front of the rear seat cushion - you can follow the contour of the headliner). The only fix I can see is to drop the headliner and attach a strip of foam to the back of the sunroof frame to keep the headliner from hitting the metal frame. I put a post on this forum for the prodedure to remove the headliner some time ago, but no one responded, so I guess no one has done this on the cars with the new, "hard" headliners.