Some technical info; The color (wavelength absorbed) makes a significant difference. Some pigments fade faster than others, red for instance is known to be least stable. Acrylics are generally better weathering compounds than enamels. That's why they went to acrylic enamels. Epoxy adheres the best and is used in the best primers. Straight enamels contain natural drying oils and tend to continue to cure out and eventually crack. So minimizing heat cycles is critical to long life here. Don't let it sit in the sun long and bake. You have to be real careful during paint to keep contaminates out of the finish until it's dried/cured. Dirt/dust can penetrate during the first month or so. Wait to buff out. There are paints/coatings that can last almost "indefinitely" but of course the price goes up and the color choices are limited not suited to automotive styling. Mostly industrial or roofing. UV is the main culprit that deteriorates the coating besides exposure to the elements. Water, salt, etc. can penetrate the coating and once Mr.Rust starts, it spreads under the coating and lifts it. Just sand around an old paint chip area and you'll see how far back it's rusted. The clear overcoat paints are best. The new ones use urethanes (oven cure) and the old lacquer jobs with clear- over are the best finishes in my book. There's no pigment in the topcoat and they put other inhibitors in it. The pigmented layer is kept deep, protected, and less subject to damage. You can clean/sand and polish the clear and reclear without damage to the pigment layer. EPA has about shutdown lacquers due to the high solvent content that causes smog etc. I don't like(have no experience with) these new waterborne coatings, because I think it's a function of how well it's cured and they haven't much data yet. I'd be certain I fully cured the pigment layer before clear. Trapping water would cause cloudiness/haze over time. So if you want to protect your investment, store indoors as much as possible, wash it thoroughly and dry after use, keep it waxed with a high quality wax. Fix any paint chips to bare metal immediately. It doesn't take long for rust to start, and it'll creep right under the paint. Seal it out. Even just waxing over will hold it til you can fix.
As stated above different colors hold up better over time light colors seem best metallic being the worst from my experience. Black needs the most work looks the best in my view. People always ask what kind of wax I use and I tell them its not which kind but how often you use I like to see water beads when it rains. I think most car companies have produced some models that had bad paint or primer in the last twenty years. I find it relaxing washing and putting on a coat of wax or what ever they call it now. when I was in high school my uncle always had blue Coral on his caddy. I use to use that on some of the cars I had lots of work but did give nice results. My grandfather who was early car person that tree sap and bird dropping and dew were the worst things for a cars finish.
