3D car models for posters

I think that usage of 3D model (with royalty free licence) in this way should be OK (you cannot only resell the 3D model).
It can be only problem if the car model is branded (BMW etc.). So if you want to make real posters for selling you would maybe need assurance from the brand owner.
But 250 copies is not so big amount so probably you don't have to solve it.
Maybe somebody else give you more info. )))

If it's a 3D model of existing real world car, then you have to approach makers of that car (not a 3D model) and obtain permisison for commercial use. If it's a fictional car, the depeding on the license, you should be good to go.

Use Proterra bus :-)
https://www.cgtrader.com/3d-models/vehicle/bus/proterra-electric-40-foot-bus-aon-center-chicago-octopus-livery

Proterra does not prohibit the use of the trademark.
I talked to them personally. They themselves gave me all the data