Do you think there is a difference?

Myth busters said no

Makes no difference.

I got so sick and tired from arguing this with some pals of mine, that I finally broke down and did some CFD analysis. Conclusion: It's actually better to keep the tailgate up (although the difference is negligibly small).

IMO, keep it up. Bedcovers are not suppose to help any either!

The Myth Busters conclusion is that by having the tailgate down you lengthen the bed and have more down force on the rear tires.


That said, I wonder what the difference would be between tonue cover and no cover, and no tailgate vs tailgate up...


Another good one they did was windows down (turbulence) vs A/C. The CPU #'s said there was a big difference (with A/C using more fuel), but raw data showed that the CPU #'s were off. A/C still used more power, but it wasn't by much.

The momey saving isn't really worth all the thought that goes into it. I say run tailgate up and A/C on

its been proven over and over. Leaving it up creates a low pressure zone in the bed pushind air out and making truck more aerodynamic. Leaving it down creates turbulence low in the bed. watch a cup in the back as you drive. It will slowly move around and then if it gets higher gets sucked out fast. That is the low pressure area in the bed acts like a bubble.

and yes running with the Ac on if far more economical than windows down. Air coming in the windows creates drag and high pressure in the cab.

Yeah, the higher engine load with AC on was offset almost as much by the less wind turbulance as with the windows down.

Another test was following a semi at different distances. Tailgating real close showed no fuel savings. ( even if there was a savings, be offset by the rock chip repair )
Seemed the sweet spot was a little less than normal distance.

+1

and you are worried why