I'll chime in here. You are right it will not be easy or quick, but the result would be very nice for visual orientated people (like me).
I like Saand's ideas for a graphic. I also think that just organizing all the pics of the different mods we have would help.
You could make an animation with the worst aerodynamic shape (cube I think) and move it towards an ideal (box fish) design. With each change add a pic of the mod by it's self (off to the side) and the coefficient of drag improvement for that mod. Rolling through a 5 min animation will cover most of the mods and show the possibilities of what can get done.
If you want to gather data for the aerodynamic shapes, graphs, pics, diagrams I would point you to this:
Reference threads on aerodynamics - EcoModder
You could use this or you (we can help with the formatting) make a new page under the Wiki main page>Reference Material>Aerodynamic graphs, charts, and ideal shapes .
I would love to see more information about this topic, when I went to mod my car it took some digging to mentally "get" what my car should look like.
With saand and I being ~12 hours different in time zones (you are in the middle) one of us will be around most any time for you to bounce ideas off of or help.
As for pic copyright issues, we can see what the rules are for images uploaded to the site, I think we have the right to reuse them within the ecomodder domain (wiki included). If not we can ask users to add the pics and then we compile them.