My brother-in-law, who has painted a jillion cars, concurred that VHT Brake and Caliper paint would probably make a super-durable finish on those interior parts, but he had another suggestion. He happened to have a couple spare cans of satin black VHT Hood, Bumper & Trim Paint, which he claimed is almost as durable. It says on the can, "FOR METAL, PLASTIC, FIBERGLASS." I gave him ten bucks for the pair, Check it out:
https://www.amazon.com/VHT-ESP027000-Black-Bumper-Paint/dp/B000CPAVBG