You guys are kind of doing the pie-in-the-sky thing. You aren't going to convince truck manufacturers to make massive design changes that won't work universally with all applications. Drivers/Owners won't buy them (I mean, I might, but 90% won't). Trucks are a very conservative beast, even the newer aerodynamic designs like:
Freightliner Century class:
and
Peterbuilt 387:
are not universally accepted. You see alot of the freightliners on the road because they are cheap, but I see more of trucks like:
If people won't accept the frontside of the truck being aerodynamic they certainly aren't going to accept any weirdness to the rear end. I hope they change soon though. Trucking in this country could save a ton of money with good design changes, but until then I think discussions about how we can change existing designs is more useful. (along the lines of the mod discussions about production cars).
PS. the Cummins white paper is dead on regarding fuel consumption. I really appreciate that link, I had read most of the information elsewhere, but it quantified the loss due to tractor/trailer gap nicely. Every 10 inches beyond the first 30 inches results in ~2% increase in drag which is ~1%decrease in fuel economy (although when we enter the realm of extreme reduction in drag that 2 to 1 ratio will not hold). So, when not hauling extremely long product I could gain ~8% in fuel economy by adding an accordion style kamback.. It would probably even be more because of the nice curving slope on the back end. I very much worry about the effects of either the ruffles of the accordion or the flappiness of some sort of canvas, can anyone comment on this? 8% fuel savings represents about $300 a week.