Aerodynamics & Diverting Wind Resistance ?

I'm at work and don't have time to read 4 pages right now in case anybody else mentioned it, but there is a website called ecomodders.com that offers a lot of info on fuel mileage gains. Not just in modifications-as the name would suggest, but also driving tips, etc. Some of it way out there, but regardless, a lot of aerodynamic mods done to the rear of the vehicle to reduce the suction effect of a blunt ***-end. Thats why you see those flaps on the back of semi-trailers to help steer the wind to blend back together.
Thats why the Daytona and Superbird also got the back window treatment along with the pointy nose.