Pete,
I think that they should be run too! We run most of our "collectibles." Why not, unless you are saving them for an investment. Even then, I've seen some used, but in mint condition, go for a rather steep price on ebay.
The only cars we haven't run yet are these state cars and that is because we just haven't taken them out of the box yet! Been busy building these days. Still waiting for my tower, so I am doing another structure so I can try your ink/alcohol weathering technique! I may even try to paint a couple of little cars that I want to try to put together later today. I also just won a bunch of military pewter stuff for the military base I am putting together. I never worked with that either but I will have to now. (any suggestions?) 18 packs! If only I would win the lottery I wouldn't have to work and could spend more time! What a fantasy!
Dot