"The Frame Extension device is designed to not interfere with the operation and loading requirements of a rear door vehicle.
The two side panels and top panel of the invention are inset from the outer edge of the frame less than 3 inches whereas the bottom panel is structurally designed to support loading and off loading operations. Properly sized, this technology will increase fuel economy up to 6%."
6% would be real nice! Looking at the pic, it's a sorta Boat-Tail that one could add to a squared off SUV with some tape and Coroplas.. 
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But this undercarriage in-flow stuff:
"Undercarriage drag results from high-energy flow entering the underside of the vehicle and impinging upon the various structures and components. The Mini-Skirt invention redirects and captures the majority of the undercarriage in-flow through the use of a vortex induced upwash field. Compared to traditional single panel skirts the novel inner and outer skirt surfaces of the Mini-Skirt invention allow for the blockage of a greater amount of undercarriage in-flow for a given skirt drop length.
The outer skirt surface of the Mini-Skirt has an aerodynamically sharp lower edge that is used to generate the controlling vortex that induces the upwash field. The induced upwash is then captured and redirected by the inner skirt surface. When installed in accordance with design requirements the Mini-Skirt technology will increase fuel economy up to 6%. "
This has me more than a little confused. Two side skirts? With one that is inset behind the outer.. Where it redirects upwash air into downwash?
And this downwash air pressure blocks impinging air better than a "traditional single panel skirt"??
I need some diagrams.. 
Found some:
http://www.solusinc.com/miniskirt.html