vehicles

Here's another source of N scale vehicles that you may be able to find at your local grocery. The "Bonus Game Token" scales out close enough to N scale to work, even in the foreground (after they're painted, of course). There are 30 models available of different US prototypes from the 1950s to the present, but they're a limited production, so get them when you see them.

Use those undetailed cheap plastic automobiles as loads for your covered autoracks. The rack's perforated side panels will prevent the viewer from seeing any details on the cars within it, so all you really need on the load is the general shape and color. This autorack is an HO scale model.