I have repaired some shallow gouges in door panels by applying low heat from a heat gun and working the softened plastic that got rolled up on either side of the gouge back into place with various plastic trim tools. Keep in mind, the heat needs to be very low. Then I scuffed the areas with red and grey Scotch-Brite pads before primer and paint.
I don't know how deep the gouges are in your panels but if they are real deep and there is not any rolled up material to work with, there are plastic filler products out there but reproducing the grain pattern might prove difficult if the area is large and highly visible...