Exactly. If you are forced by design to use a un-aerodynamic shape (like a large 53’ long box, 8.5’ wide) and you are forced by design that you cannot do standard aerodynamic treatment (no extra length for a permanent kamm-back on a max length semi trailer) then just maybe you could improve fuel economy by having active blowers enough to offset the power to run them. Weight becomes an issue though, how much would all the active blowers, high efficiency motors, controllers, etcetera weigh? Also where do these blowers go, inside the trailer volume? Tractor trailers operators need to be able to haul a full load, which is typically either limited by volume or by weight. It would be a hard sell if the trailer weighted 2-3k lbs more, which meant 2-3k lbs less cargo or was 2’-3’ shorter which meant 2’-3’ less cargo. At that point, assuming full loads you have to consider that it might take more trips to move the same amount of stuff, so are you really saving any fuel overall?
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