Ken Fry just fried my brain.
I'll try to wrap my head around sailing down wind faster than the wind again later, when I'm not quite so tired.
My idea of harnessing wind is to have tall smoke stack type structures alongside the road with gaping open-mouthed elbows at the tops. The elbows would be articulated and have weather vane tails to keep the mouths into the wind. At the bottom there would be openings that point in the direction of travel. Viola, constant tailwind.
Yeah, we're off topic, but I blame Old Mech.
Okay, I'll go to bed now.