The fun part is that car paint is significantly less expensive then its marine sibling. If you ask me, its the same stuff, but you pay extra for the word “marine”. A fellow Wayfarer sailor has repainted his boat using cart paint all the way and it still looks like new after five years.
A well-known boat painting and finishing firm has professionally spray-painted quite a few boats from our sailing club (and many elsewhere) in recent years (admittedly most/all? of them woodies). I’m not saying they use car paint, but if you ask what colours are available you’re likely to be referred to Halfords to pick a colour from their charts 😆 . They use a vehicle spray-painting chamber/oven, complete with filtered air etc. We had our Enterprise done a couple of years ago – immaculate finish then and now.