Coat all your weatherstrips, your interior parts, even tires! with a polymer protectant like Meguiar's protectant for plastics or Nu-Vinyl. It goes on dry, doesn't peel or yellow, blocks UV rays (one of the 'killers' for plastic surfaces which regularly see sunshine), and dries quickly to a nice satin shine. Absolutely the best "appearance maintenance" product I've found----EVER.
It's great on weatherstips, as it seals the surface and helps to prevent degradation of 'plastic' products.