Kambiz Salari of the Lawrence Livermore National Laboratory claims that for a truck travelling 70 MPH, 65 per cent of the fuel burned is just overcoming aerodynamic drag. Much of that drag come from the air vortices generated behind the vehicle as it moves, that low-pressure zone that bicyclists and hyper-milers love to "draft" in.
Saleri has applied for a patent on big fans that basically pump air into that void behind the truck, dramatically improving fuel economy by eliminating the vortices and essentially cancelling the draft. I wonder if Richard Nixon should not have priority on the patent? ::New Scientist