PLA will be better for hardware store and hobby junk. You cannot use automotive class finishes and expect them to last. Generally stick to one brand. Most paints are formulated for steel. ABS is the closest to steel in thermal properties. The expansion is the most important attribute. PLA has a different thermal profile so catalysed 2-part paints will not work very well long term. Rattle can enamel is junk by comparison, but it never fully cures like automotive paints. That property helps it stay in place longer in general. There are special adhesion promoters like bulldog for automotive stuff, but the thermal properties will still be an issue.

Pro automotive paint is 99.9% sanding and prep work. It is far more intense and rigorous than people realize. Perfection happens in the prep work. The actual paint is just a way of showing off that perfection. Mastering automotive paint is actually all about defeating yourself. Perfection is not subject to your emotions or expectations. It is right when it is perfect.

You want the highest pressure spray cans as possible. Also, if you do not used all of the can at once, flip it upside down and clear the nozzle by letting the siphon into the empty void and spraying. If you have a compressor that does not shoot out a bunch of oil or water, a cheap Harbor Freight pink gun with the nozzle of the can beside the spray gun will work wonders by atomizing the spray far more effectively.