an interesting idea... i've always wondered it it was possible to design a sort of "wing"in the broad sense of the word, that in stead of generating lift at the top would generate pressure at the end... there would naturally be a loss of energy, but if this shape could be roughly car like than you'd have a car that in stead of having drag at the end would have pressure at the end.
a quick google search generated this image
wich reminded me of something else... this:
i admid a rather loose association, but still....