I've now tried the Plasti-kote (but the weather has not been good for spraying). I've had the following results. The finish, while reasonable, turned out to be soft. So soft, in fact, that I got a black mark on my finger when I ran it over the paint.
Plasti-kote tells me that I need their lacquer over the top, but even then it won't be weather resistant. I want it for a car and they say it's not likely to be suitable. They couldn't say why the finish was soft, because apparently it shouldn't have been.
But as I said, the weather has not been good for spraying.
Rob Graham