I will say that it will not hold up used on an exterior surface on top of the car. Well, it will hold up, but turn to a flat dark gray.
Last October my Son managed to find a pine tree that jumped out in front of him as he was taking a short cut home one night through the neighbors yard.
Fortunately, I had just removed my stock Laser Red hood for my paint job. It still had good paint on it, so we sanded it down with 220 and then 320 wet or dry and I sprayed 3 coats of SPI black epoxy on it and the front bumper cover.
Here we are 10 months later, and it is now a flat, dull dark gray. If it has UV additives in it, it must not be enough for direct UV all day, 24-7.
1966 GT Fastback, restoration almost there! Code T Red with White LeMans stripes.
2015 GT Fastback - Deep Impact Blue