I think the coal car looks great. I agree about the engine...it looks uniformly sooty, but below the cat walk, there doesn't appear to be any weathering (but that could just be my monitor too). I'd expect everything "below the water line" to be a lot more rusty brown and neglected as the cab area appears. The boxcar's roof could easily be toned down and silvery run off finding its way down the side of the car. For your first time using paints - my hat's off to you because I know first hand that there's a smaller margin for error using paints than chalks. Really good job.