A previous thread here on the subject had some good info on page 3 and 4.
http://ecomodder.com/forum/showthrea...ds-2914-4.html
http://en.wikipedia.org/wiki/Fineness_ratio
This image matches the pink smoke trail from page 1.
As was brought up in that thread, turbulence isn't the only thing that makes resistance to motion. Visualize an open door flapping in the wind. A very small air pressure difference on one side will slam it around very hard by causing many pounds of force over the area of the surface.
Making the nose more pointed reduces the pressure in front of the car, eliminating many pounds of force that would be pushing backwards.