I have a 99 E300 and when driving over bumps or pavement separations in the road, I am getting "thud" noises coming from the headliner just behind where the sunroof shade slides all the way back. I could literally push or tap it up against the roof and the noise was identical to what I previously thought was coming from the rear shelf or trunk.

Now, the question is.... how do I fix it so that the headliner doesn't bang up against the roof when I drive over bumps or separations in the pavement?