I've used 303 Aerospace Protectant on the rubber and plastic trim (and tires) on my cars for years.
I like it because it doesn't make things to shiny/greasy (like Armorall). And, they claim that it has UV protectant.
I will say, the rubber and plastic trim on my cars never seems to age, for years or decades. Is that because of the 303? Can it really prevent sun damage?
So I decided to do an experiment. On 80s BMW, the "chrome" windshield and rear window "lock strip" trim is actually plastic "chrome," covered by clear plastic.
It is infamous for discoloring with a few years of use, first going to brown, then to completely black - like this
I took a brand new piece of that trim and nailed it to a board.
On half of it, I applied 303. The other half, left bare.
Then I put it on the roof of my house, exposed to the elements 24/7.
I reapplied the 303 occasionally, every 3-4 weeks.
FOR THREE YEARS!
The results have been pretty surprising. I'll pull it down tonight and post pictures.