As you see the tail of the most efficient vehicle of the world is a bit quite longer :
ETH - PAC-Car II - PAC-Car II Miscellaneous
The speed is only of 18 mph. The lateral wind is considered.
http://www.amidesign.ch/PAC_CAR_GENEVE_2006_0033.JPG
The first rule for aerodynamics is wrote in a stone.
Aerodynamics rule 1 .
As exemple the NACA series at 20% thikness:
NACA 4 Digits Series
But people speak of laminar airfoils. Better for Human Powered Vehicles. But it is extremly difficult to achive those technics. A big precision is need to respect the ideal shape. Sailplanes factories use this technic. But for how much money. A good old WWII propelled airplane achive a Mach 1 top speed in dive.
I have also a project of an electric car :
http://www.alekscar.ch/Archives/CAO.pdf
Alekscar.
But it is for later. Maybe for half 2009 or end 2009.