Check this article may be it will be interesting for you: http://www.carbodydesign.com/2013/06/pininfarina-sergio-concept-the-design-process/

It is about Peninfarina design workflow. They use Creo and moves like this:

1. Sketch
2. 3D sketch
3. Polygonal(SubD) 3D Model
4. Nurbs.
5. Production e.t.c...

In third stage they use polygons becouse it is much faster to build and reshape forms. And only after they satisfied with forms they go to nurbs for precise modeling, class A surfaces e.t.c.