Pickup bed aerodynamics idea. Any thoughts?

[hat_man]

Thank you all for the input. I apologize for not getting back sooner, but my work schedule has changed and this crazy heat has just exhausted me. Like I have said before, with almost an hour or better ride each way to work it gives me time to let my mind wander in different directions when it comes to ways to improve my little truck.

Bondo...that extension is K%L and the cap is amazing!

Yesterday, after reading all this info, and driving all the way to work just to be told that they were calling it off because of the heat, I had another idea. If I were to do some sort of extension arrangement following the lines of my intended aerocap and pair it with at least a partial (rear) belly pan from approximately the rear axle to the bumper, how could I also extend the belly pan out to the length of the extension and make it secure but still removable? Even if the angle were to change (axle to bumper/bumper to extension) would it be of any help or just way to much work to see any noticeable gains?

The only other thought I had was if I built the extension could I also remove the tailgate for weight reduction as I really don't haul anything anyhow. I did when I bought the truck but don't now.

This truck is paid for, runs great, and gets great mileage (30/highway but I'm shooting for more). Please don't tell me to get rid of it and change to a better mpg car like some on here would do. I have heard it before "Why try and mod a truck they are aero be damned anyhow. Get a car and really do it right. etc." I like being able to sit at lunch with a bunch of construction guys (with their BIG trucks) and tell them that I get about 10% better mpg now than when it was new and am trying for more, when they complain about how much they spend a week in fuel. This is my daily driver and my pet project and I love it.

Again thanks for all the advice on this idea and the others I have posted before. You all are a big help.

[aerohead]

The boundary layer in the aft-body of the Ranger has got to be handled with kidd gloves if separation is to be prevented.
For your diffuser and cap extension to function,you'd need a really well executed belly pan upstream.
Cleaning up the sides of the truck would also help provide clean rectilinear flow to the beginning of your new 'sink'.
Front wheel gap-fillers,wheelhouse rear edge radii,rocker panel extensions,flush wheel covers,and rear wheel skirts would all help provide the cleanest flow at the rear.
Then,your cap and diffuser extensions would have their best performance.
Also,you could add in vertical sail panels behind and to each side of the tailgate,which would help tailor the new wake.You'd trap a vortex in the outer sides,with re-attachment at the ends and end up with a smaller wake of higher base pressure,netting you additional pressure drag reduction.
And the added weight would be offset by the tailgates removal as you've already mentioned.