Rattle from rear with top up, disappears when down

I went on a 15 mile round trip drive yesterday, and my 2001 2.5 developed a rattle from the rear. There had never been a rattle before. Started small, like something in the trunk. Got worse as I neared home. I thought the trunk lid might be unlatched. It occurs when the road is bumpy.

Drove car today, and it rattles like a loose shock, when I go over bumps. I put the top down, and the rattle went away. Amazing. The top does not apear to be loose. I recall the weak rear shock mounts, and thought that a likely candidate, but why would the noise go away with the top down? And it's not that the rattle is masked by road noise with the top down. It's VERY noticeable with the top up, and not discernable with the top down.

I'd start there.

I had the same problem. Sounds just like a shock absorber or something. Can't hear it with the top down. Try this - drive under an overpass or tunnel with the top down, or even somewhere against a wall, and you'll hear it with the top down - the sound will bounce off the wall and get back to you even with the top down. Anyway, I took it to a BMW specialist, and they said it was the license plate bracket. It wasn't. I then lived with it for months and months. When I returned to the shop for something else, I asked them to look at it again. It was some kind of heat shield under the car that covers the exhaust or something. They tightened it and the problem is gone.

That's a new one. At least I haven't heard of it. I have a 2002 2.5 which I believe is pretty much identical to the 2001, so I've been watching this thread. Thanks.

Its the rear shock mounts. they fail every 40K miles or so. The reason why you dont hear it when the top is down is because the top covers the the rear shock mounts when it is lowered. Peel back the carpeting in the area where the top rests when it is lowered to get to the shock mountes. Chances are that the rubber is worn out.

have become loose and the pressure from the top down stops the rattling. I would tighten down the shock mounts more and see if the noise goes away.