Of course a lot of design visualization is done by auto makers with 3D modeling software. If you have no sculpting talent it might be just as expedient to learn to use such software. Your completed model could be rotted to any angle on the screen.
With specialized 3D software you can create a model that can be output by a 3D printer service, like these designs people offer for sale:
http://www.shapeways.com/search?q=car
NHK News was just doing a piece on car design prototyping, including a life size clay model as I was typing this, maybe you can find a replay.
Car designers never ask how.
I want to design a model car at home but hae no oil based clay. Is there any ideas or methods to do this. I was thinking start with something hard and sand it down will work but i dont know what material to use?
