Repeating myself . This may be the most important place to say it. There's very little paint in spray cans. Any quality brand of spray paint will cover and look good initially but...
your arm will wear right through it at the top and you shoes and set belts will ruin it at the bottom of the doors. It just goes on tooo thin.
i painted the inside of my current doors with gloss black appliance epoxy (spray cans) and while it is holding up better than the avaerage spray enamel, it's too glossy and shows every finger print.
My best advise is have a paint shop use real single stage car paint from a real paint gun. Do it once and do it right.Make a day of it. Remove the door panels, door vents, cat whiskers, scuff and prep, and mask.
The best way I've found to clear/mask the vent window is to remove a few bolts and lift the assembly. not all the way out but enough to paint under it. If the door were to get closed with the vent window raised up it could become a very bad day. Be careful
Ok, I can spray them myself, I have a gun. Doors aren't on car. They were painted yellow by the gentleman I bought them from. Is it just a gloss black or is there an official "name" for the paint.