one of the best tut about the spirit lines of nurbs in direct process concept car design is this one! ;)
http://moi3d.com/forum/index.php?webtag=MOI&msg=898.4

Hi michele,
This forum is invaluable to learn MoI and Nurbs modeling in general.

For a long time I couldnt figure out "How someone could create a car" as when I started modeling one for myself, trying to make 1/8th inch sheetmetal would take all my resources of my computer to make 2 doors!

After sticking around here a bit I found that only surfaces are used to do this.

Here is a link from awhile back that has a model you can load and look at for inspiration and reference.

Good luck,
Burr

http://moi3d.com/forum/index.php?webtag=MOI&msg=1408.1

THANKS to all very much!!!
You're great! Now i go to study!!!!!!!!
soon i'll update some test

ciaoo