Good post and lots of good info.
I do have more than a few of these:
(http://www.jbrr.com/Pics/Vehicles/IMG_1743.JPG)
Though I normally keep them outside all year long, I brought all of them in this year for a major cleanup and rehab.
I first prime them and bake the paint for over an hour. Then I put on the finish color coat and bake it again.
All of these have now been sprayed with clear Krylon. The rubber tires do not hold up well outside, especially the white ones. I have replaced the tires with some Magic Sculpt. I have also used JB Weld to fill cracks in the white tires, then repainted the tires.
The other thing that goes is the chrome. I paint all the chrome pieces with my Sophisticated Finishes platinum paint and it holds up very well.
I usually skip the motors when I’m building these, and I don’t need to open the hood. In fact, I glue the hood in place.
These are all ready to go back outside in the spring, or maybe even a bit before.