Hi
I Had a very annoying rattle on my Transporter T4 and i worked it out to be the interior rear view mirror glass rattling in the housing, i wedged a very small piece of paper in the corner to solve the problem,Also had the problem on the bench seat if carrying a passanger the flat metal base to the seat would pop up and down creating a moderate popping sound.
Hope this helps
Debbi
October 2008