I'll save you (but mostly myself) the time, the old Lamborghini Countach had the world's lowest drag-coefficient, you can take that car's shape and put it to the test anyday, wheels and all...
Here's another:
http://cr4.globalspec.com/PostImages...FE10BC3519.png
It's a simple thing, starts with a point, ends in a point.
No getting around it, that is the world's most aerodynamic shape.
Actually the newest Lamborghini Veneno is super close, too:
http://en.wikipedia.org/wiki/File:La...profile%29.jpg
Now my work is done.