Does anyone have any rules of thumb for the approximate aerodynamics of full size pickups, primarily chevy/ford/GM, but not only including the latest/newest ones? I'm curious how much things have improved from say the 80's to today and whether any of them stand out or if they are all about the same. What little i've seen suggests the aerodynamics of a brick for dodges, i've seen Ford windtunnel tests designed for efficient tailgate up towing - and wondered whether the truck itself is a bit swoopier because it actually is better aero... or if that's just styling.
I'm sure there's lots of other posts and I will search - this is strictly brief info/rules of thumb/suggestions for further research.
Like someone following trucks better than me if they could share any useful info they know.
I'm specifically wondering if there's any full sizes that can get 30mpg or higher at 70mph normal road speeds, whether through teardrop bed covers or whatever, but without excessive focus on extremely numerically low gearing. (future project to research will be a tow vehicle for 5 tons and up loads either 5th wheel or preferably gooseneck, main goal being to boost mileage while unladen or with empty trailers, and while moving low dense heavy material on flatbeds) As an interesting story of point I once met a guy (with previous owner claiming the same) who had a 44mpg Suburban... it was some modified isuzu diesel in it and still had enough power to pull a horse trailer. He probably drove it real slow but I still find that mindblowing if it's even possible despite hearing good things about cummins/isuzu 4cyls approaching 30mpg without any aeromodding at all.