new member-exhaust fumes in interior ???

I've replaced the seals on the rear hatch with some success, still not perfect. When I bought mine I spent a few nights washing her down to remove a lifetime of residue, by far the dirtyest spot, surprisingly, was the rear hatch closure area. The bottom and sides were blocked with black exhaust crap (very hard to remove) - that kind of verified for me the entry point the fumes.