I just checked by door bottoms and found a little bit of bubbling, hey, it might even be some welding spots, very minor, no rust to see. Good idea about the plastic caps down below, removing them would create some better circulation. I hardly ever drive my toy cars in the rain or snow, so this should be a minor problem for me. It looks like I could drill some drain holes in the bottom, but I'm not sure they would be the VERY bottom, to get a good drain of water. It might cause more problems down the road later.