Awlgrip is a polyurathane it is very scrach and chip resistant,
Imron is also a polyurathane from dupont and can be tinted to almost any color its sold at almost any body shop supply store that sells dupont.
Endura is another polyurathane that you can get in most colors
I have used all 3 and they seem to be the same, just sprayed them though, never tryed to brush them.
Urathane automotive paint stands up almost as well but if you scuff it or it starts to fade over time you can polish it and it comes back shiny
Polyurathanes tend to go dull or chalky looking after you polish them so there is a bit of a trade of there.
I have used regular 2 part aoutomotive urathane to paint many boats right down to the water line and have never had a problem
I faired an painted a 54' steel bruce roberts about 7 years ago I painted it with duponts automotive base clear system and it still look great today