Refinish Restorer. Found this product because of fading on my Cadillac Escalade EXT tonneau cover. Worked great, lasted about one year, but the vehicle sits outside in the sun, rain and snow.
Also put it on my

faded running boards. One year and they still look as good as the day I put it on, (but my

gets to sit in a garage). Fading has not come back, and just use a vinyl protectant after I wash.
If you google Refinish Restorer, I think there is an on-line retailer in the US.