I would not recommend trying to play with nurbs if you are just starting out. The process involves laying out curves that follow prominent body lines and then using those curves to create surfaces which are then converted to polygons.

I would recommend sticking to polygons and either using box modeling or an edge extrusion workflow. For auto body modeling the edge extrusion workflow is probably the best way to go.

You might want to also go to theblueprints.com and look for a set of blueprints that you can use to reference the various orthogonal view to model against.