Ok, I have this problem that's driving me NUTS! I have a 2003 MCS and I noticed that when I have the rear seat down I get this odd squeeking when driving. Maybe it's more of a creaking sound. When I put the seat up, the problem goes away. Does anyone else have this problem or know the cause?

I used to have a squeek from the dash but the dealership fixed that one.

 

yeah..my 06 sometimes does it!!
then once i put the seat up..it will still do it sometimes...have to push around on it to make it stop...

 

Same with my '06MCS

I figured it had to do with Chassis flex and one of the mounts or hatch rubbing when the chassis flexes...

In my other toy, less-stiff-than-the-MCS 1986 Porsche 944 Turbo...
If I had the sunroof slightly vented when exiting my old driveway, first the right wheel, then left dropped off the driveway "ramp" onto the road, the sunroof would groan and if you watched, you could see a *slight* distortion in the crack between the interior, the opening, and the panel...

Doesn't make it right, but then again, a rear "strut" brace (ala GP) should help with that issue... (I just don't run around with the rear seats down that much...) ALSO, there is a lot more noise with the seats dow nand rear shelf off that when they are in place...

HTH