Martin, I have the impression that the access hole in the fiberglass underbody over the fuel accumulator is common and may even be present on all DeLoreans. This hole helped considerably on my car when I replaced the fuel lines. I thought at first that this might have been done by a previous owner, but the cover plate looked too professional. It is gray plastic with a layer of foam tape to make a gasket. It has a slot on one side that goes under one of the two posts that hold the rear console down. If this cover were missing, it could allow a lot of road noise through. About the "rubber grommet thing" under the shift boot, I talked with another DML member who had it missing on his car too. He bought a new one from a vendor. I'm sure that this missing is the major cause of your road noise. Walt