You imply that fish actual understand and knew about turbulence and aerodynamics 2 million years ago and then call 2 people on this thread dummies because their understanding of fluid flow and drag doesn't equal yours. Did the fish design themselves this way? I hear they attend school, so who knows for sure.
The curved hoods atop most cabs these days don't do anything compared to what having a real fix to the back of the vehicle would do. Exactly as you suggested. Problem is, that the fin/tail needs to be much longer than is practable to drive around trailing behind you or an alternate design would wipe out over half your carrying capacity to maintain the same length. Either way, it's not going to work and that is why we don't see tail or wing shaped cars and trucks on the road everywhere.
Again, the PERFECT is the enemy of the GOOD. A short tail in the 10’ to 15’ range would eliminate MOST of the rear drag, even though a 30’ to 40’ long tail would be perfect as per this kamm effect. Truckers don’t care about PERFECT, improving their mpg is all important to them, even a 50% reduction is GOOD NEWS.
Like all the other critics here, you try to mask laziness with our know-it-all brickbats. The simple truth is that you and yours do NOTHING for the energy picture. I and others like me are trying to HELP truckers and our ecomony in general by improving the aerodynamics of inefficient semitruck boxes; the aeroshell is a GOOD start, now the bookend TAIL.
You people remind me of what Jesus said : Lawyers, liars, pharisees, hypocrites; you load burdens on other men’s backs but won’t lift a finger to help. And as it is said : no one ever built a monument to honor a critic. If YOU and yours are ever going to ever be WORTH anything, get off your dead ***** and DO something worthwhile.