Go to NMRA (National Model Railroad Association) site for scales on all your
> favorite railroad letters. G gauge (scale is incorrect) model railroads
> encompass several scales.
Yes, the reason that they call them gauges instead of scales is that they refer to the width of the track. Different real scale railways using different gauge track will scale out differently. I also suppose that the relationship between the gauge and the scale of the cars might not be religiously observed.