I had the car permaplated when I bought it and it was supposed to have some protectant for the interior.
I don't know if I'm imagining this, but it seems like my orange fabric might be fading, the rear headrest most prominent.
I've used RaggTop fabric protectant for a canvas convertible top and it has UV protection. It also beads water to some extent. I might give it a try on my seat fabric, of course on an inconspicuous spot for starters.
RaggTop also offers a cleaner but I don't know if it would do more damage than good.