I like the drafting with a buddy idea...at least you know he won't be pissed if you are on his bumper.
Back when I had a 1972 Honda CB450, I would only get 150 miles on a tank of gas...unless I drafted. I would ask permission from the trucker to draft, and most would say yes. It was very difficult to stay stable back there because of the eddies (turbulence) comming off from the back, but I would get over 200 miles on that same tank of gas if I stayed in the draft.
The eddies that come off from a truck moving above 65 mph are so strong that they literally will suck the car along when in the eddy if you get close enough. Moving Van semi's do this the best because their trailers are closer to the ground. (and you can test this in a swimming pool with two people. I've "towed" my daughter across the pool just by using the "draft" of my body once I got us both moving. I would take my hands away and she would stay right with me as long as I moved quickly through the water.)
Now, if you really pay attention to drafting in NASCAR, you will realize that several cars drafting in a line together use less fuel and go faster than a "train" of fewer cars drafting. Again, it has to do with air flow around a "body". Longer "bodies" create less drag than shorter bodies, even if both have the same cross section.
Engineering is fun.
