Tonneaus are dependant on truck cab design & bed length.
I am always up to the new information & will adjust my perspective accordingly, but all I have read and researched so far leans in favor of a tonneau to decrease the 'high pressure' volume in the bed = less secondary turbulance = less air resistance.
I have one advantage already - I bought a 5'7" bed (the short bed) which along with my supercrew cab actual offers the BEST aerodynamic signature for a fullsized truck with an open bed. Ford designed the rear of the cab to pull air down into/over the bed of the truck, but in a smart move - they actually have it 'aimed' to flow over the bed and flow over the top of the tailgate. as soon as you go to the 6.5' bed, it does start to JUST catch the back end of some of that overcab airflow - the mid length & long truck beds always benefit from any form of bed cover. Even only covering the rear 1/2 of the bed to aid with rearward airflow.
F150 Aerodynamics;
Truck Tailgate Up/Down research;
Ecomodder thread
http://ecomodder.com/forum/showthrea...down-3904.html
Pickup Truck Tailgate Up Or Down Aerodynamics Tested | New Industry Products | Trucking Times Magazine Trucking Times
Driving With Tailgate Up Is Fuel Efficient : Discovery Channel
Canopy test;
If anyone has any new information - feel free to share it as I am trying to both help myself and anyone else who's interested. So far I think my research about which truck to buy and adjusting my driving habits is just a start
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