Someone said the Geep on display at Horseshoe Curve is pretty accurately painted. Or at least was. A bunch of years ago when I as last there (at least outside, to see the loco - I’ve since been there on the other side, riding Amtrak through there), it looks very much black, perhaps slightly metallic. Until you moved around so that the sun reflected off it, then you could see the green. That was some 14-15 years ago, sitting exposed to all weather it’s probably a lot more faded now.
–Randy