When it comes to loading a 3D car, in opengl, do I have to load the car with the wheels or do I have to load them separately? You know, load the car, then load the wheels and then place them at the specified points, because I want to steer those wheels and to animate them.

I am fairly new to loading 3D objects in raw opengl, I was able to load a tree, which is a simple model.

Thanks!

This depends on the software that exported the car. Most likely the wheels are already designed as submesh and already stay at the right position to steer the wheels. If not, you have to define attachment points for the wheels, for example in some kind of editor and save those to be used in your application.

Animations btw. are handled differently because animations are most likely weighted matrix transformations to the mesh