Recently I had to have my car appraised for the insurance co. The appraiser mentioned there was some stuff I could buy to rejuvenate my rubber/plastic black trim.
I didn't realized how tired mine looked. I remembered having something called black chrome I bought years ago.
Gave it a try and the results were amazing. For the really dried out areas the plastic seemed to absorb this stuff. So I put it on thick and let it sit for a while. Turned out pretty good I think.
Sorry bout the pic size. Have no idea how to change that.