Aerodynamic car body design

Software for Designing:
The software for designing and engineering is very expensive. Not many open source tools are available at least for Car Body Design. However, you may try eval copies from these tools for designing. One such popular tool is:  Rhino (http://www.rhino3d.com/download.htm)

You may find this open source community available at http://www.halfbakery.com/idea/Open-Source_20Car_20Design providing useful inputs.

With respect to the Project Ideas, you may have to wait for a little longer to hear from an expert.