Tar stuff, mmmmm , they (FIAT), even used it in the 500`s, . It is there for reducing the "drumming" effect , as it has sound insulating properties, you may find its louder in the cabin after its removal, and yes it can hold a film of water but does`nt absorb the damp as fabric insulant tends to. I shall be using some of these tar mats as they are quite good. Mike.