Welcome to the forum!
I measured a non-scale (027) freight car as found in many starter sets, and it measures 2.1 inches in width. The width of true '0' scale cars may be a little bit wider, but not much. You may be able to place your model on a flatcar, but it will overhang on both sides, and will strike any switch machine housings if you have switches on your layout.

Lionel Large Scale (G scale) trains are a larger scale, and have wider rolling stock. Your shuttle craft would fit better on that scale train.

Larry