I am not the original owner.It is a 2000 ford taurus. when i bought the car, it had a pioneer cd player in it that is a few years old. it still had the stock oem speakers in the doors, which i yanked out myself. No plastic vapour barrier, but a thin layer of foam for sound deadening from road noise. This is what was in all 4 doors. maybe the thin layer of foam acts as the vapour barrier?