You might have to re-scale them, but this page has many wonderful cars.
These are all 1/30 scale models, but they are high quality and could be reduced. Lots of beautiful models here. At 1/250 scale, you would be better scaling up the ship. I didn't realize how small your model is. I just saw that. Models that small, they are out there, but lots of hunting, and at that size, not much detail.
Thanks so much! Both sites offer possibilities. The ship is a model from JSC, and I will stick to the 1/250 scale. It also comes with about a dozen assorted vehicles that I could also copy, but having a variety would be better! Thanks again!
Robert
The 250 scale website had quite a few vehicles. Search the website well. Everything there is free. You could repaint a lot of those vehicles in Paint, adding to the fleet.