Differencies between markers

Hi,

I have a question. I want to know how to set properly the markers on a body. I've seen that I can activate three kind of markers on a body: CM coordinates; Inertia Coordsys; Body Coordsys. What are the differencies? I have the model of a car that is moving thanks to a constant rotational speed applied on the wheels. If I want to steer my vehicle, which kind of marker allows me to define the correct rotational speed vector? In other words, I want to know how can I define a coordinate system that moves with my body/graphic.

Thanks

Stefano