No H.O. Cars;
I haven't done it to that scale. I usually converted 1/24 and 1/25 regular kits. My favorite still runs. It's a 1964 Plymouth Fury Two Door Ht. painted in A.M.T. Fire Red Lacquer! Remember that Paint? It hasn't chipped off yet! I will say this though. I am on my fourth front bumper. Those other cars keep getting in my way LOL! LOL! Mopars Rule!
Remember the Aurora sets? And the contests? You go to your LHS. Buy a car and plunk it down on their track, Right out of the Box! If you win you either get another car of your choice or Keep the one you bought and get your money returned, (in some shops!) Or the designated Aurora Prize car!
I have run slots on model railroads for moving traffic though. That actually works okay.