[aerohead]

Originally Posted by JETZcorp

I know that what I'm seeing here is no very scientific, but given that my commute is 90% highway at least, and therefore more biased toward aero than weight, that leads me to believe that the noticeable improvement in range (and coast-down) is due to the aero, the weather, or likely a combination of both. I don't see weather adding this much on its own; it certainly didn't last summer.

But, obviously the Ecomodder community is very difficult to sway, and that's great! So I tell you what, when I get another tailgate (gotta have one for ice chests, chainsaws, etc) I'll do some actual ABA testing. If the ~2mpg gain that the gauge seems to be predicting is related to the tailgate, it should be pretty obvious in an ABA, considering how many percent that comes out to.

As for safety, my rear brakes would struggle to stop a tricycle, so I don't see the rears locking. And if they try, I have ABS back there, which has never been called on. The fronts, which don't have ABS, most decidedly have locked up before. Big smoke, very scary.

When Texas Tech did their pickup truck research back in 1988 the difference between tailgate up/down meant only a 1% change in drag on average,which would translate to only a 1/2% change in fuel economy,measured under extremely controlled conditions.
With all the variables of real world driving it would be very difficult to discern such a small difference given the signal-to-noise ratio.