Mike : My observation is that is sort of depends on the basic vehicle being modeled. If in real life the vehicle was small, like say a pre-war Ford coupe, the scale might be OK however if the vehicle was originally large, like say a 1950's Chrysler 4 door sedan, then it might look too big. I am sort of a "toy train" guy rather than a scale guy so I use whatever looks OK on the layout. Remember you can sometimes use visual perspective by putting large cars in the foreground and smaller ones further away to give the illusion of distance. All in, I say ..." if you like it, then its OK!"
Respectfully
Don
