I'd love to find a couple of cars in O scale narrow gauge (Oe, they call what in the US is called On30) for German prototypes.
As I model a RR operating unit during WW2 on a stateside line, I think it'd be interesting to throw a European car into a Army train, painted in OD green or black with Army markings, much like they actually did near the end of the war and afterward at Ft Eustis, VA. It'd make for an interesting wrinkle in an op session...