[aerohead]

The aerocap,with plan taper gave me 13% at 70-mph with the T-100.A 1/2-tonneau on the same truck was good for 5%.A cab-wing/sailpanel extension of 18-22 inches,combined with the 1/2 tonneau has been shown to up mpg by 9% at 55-mph.I realized this on the T-100.Results are going to vary from truck-to-truck.-------------------------

I spent 200 man-hours on my original cap and never really finished it.You can slam a piece of primed/painted/reinforced plywood across the bed rails for durable proof of concept experiment.( house paint is ok ).