I'll throw another vote in for Bartact. This is the only photo I have handy, my covers are back from they were Trek Armor. Same company though, same awesome product. I'm on year 6 or 7 now and I go naked all summer. I recently replaced the driver seat bottom cover (my fault, not theirs) and there has been zero appreciable fading. The new cover is a perfect match to the old and the stock seat fabric underneath was pristine when I changed it.

 

Bare ass'in it on the seat cover. Now THAT is an endorsement