For interior plastic, leather, and vinyl parts, the traditional method for restoring finish is to use a product like SEM or Duplicolor spray dye. It's thinner and more durable than most paints -- though I can't speak directly to the specialty plastic "paint".
Generally though,,,parts that get touched will require periodic recoating. Parts that remain untouched should last quite awhile. For touched parts, one advantage of the dye is multiple coats don't peel/flake/build-up like paint often does.
My favorite interior black dye is SEM Landau Black