I get a lot of hits from Google when someone searches for chariots. You have to look a lot to find some good sites for miniatures, therefore I will provide links below as I find them.
Other Chariot Sites:
Ritchfield, Idaho in 2004 had these sites:
Now this is not a joke, the next time I am near Idaho, I will try to get more information. I snagged this image from their site and hope they do not mind.
I will add information to this site as I find more links.
Please note, chariot racing is dangerous. The drivers have bicycle crash hats on and are wearing winter clothes. This is not the type of class you would see at a miniature show. The AMHR chariot classes are judged on gaits, appearance of the team and the drives must be wearing costumes which must be Roman style. The goal at an AMHR show is not to see which chariot can go the fastest (although I have been at some when two very experienced drivers were there and did let their horses run a lap). I have also been at a show where the chariot broke and if it were not for the control of the driver and the fact the horse did not spook, no one was hurt.
I have included another shot of the chariot.