Ger, the bodies are a LWHT grade stainless steel. The graphics are now decals, which can be removed and replaced if damaged. The
coaches were built for Mass Transit. We built the same type of cars for Maryland and Long Island RR. In Maryland they are certified to run at 125mph. These are different than the old school Gallery type cars where the second level was open in the middle. Each level on these have a full floor and ceiling. To the passenger it appears they are in a regular coach on both levels.
If you look carefully you will notice that the lower level passengers are sitting below the edges of the wheel. This along with heavy boxed girders underneath keeps the center of gravity low for stability. This was proven when one of them hit a rock crushing machine last year at a crossing and was knocked off the tracks but did not turn over. I have a lot more pictures if you are interested.
Next week I am teaching classes on NY subway cars.