The car body is one of the hardest things to make inside a nurbs application, but if you don't care about a perfect tangent of surfaces the work come more simpler, below a new file with simple surfaces builded from network curves, but for this type of shapes, the best workflow is, creating a simple surfaces to be used as constructions or for auxiliary curve building and projection and after when you have a well made constructions curves you can do any type of surfaces, but is an hardest work.

You can take those video as a references, and for understanding the complexity of this type of surfacing.
https://www.youtube.com/watch?v=Y3KbskU1IAw