"Scratch-resistant plastic parts" is more than a phrase with great appeal to car buyers. It also presents a great challenge to automotive Tier 1s to make sure these parts perform as promised in the real world.
Many suppliers meet this challenge by mixing a small amount (typically 1 percent) of migrating additives with polymers prior to injection molding their plastic parts. After molding, the plant-derived additives accumulate at the surface to form a thin film that improves scratch resistance.