I assume the Marx car is tinplate? I use Draino to remove paint from all my tinplate stuff. Soak in a strong solution for about 30 minutes, more if needed. all the paint should come off easy with a stiff tooth brush. Rinse well. If the car has been repainted it will take longer to remove the new paint. If there is still rust, fine sandpaper should work...you can also use navel jelly or a wire wheel on a Dremel Tool for the rust... To repaint start with an auto etching primer. I use any good spray paint...I use what ever company has the color I need....After painting I bake it in the oven for 30 minutes at 200 degrees. Good Luck
