Sorry if this in in the wrong group, but I couldn't find one that matched the question:

Does anyone know the average fuel mileage gain to be had by driving without a tailgate on a truck with no tonneau or cap? I need to justify the purchase of a tailgate net or louvred tailgate (5th wheel style).

I don't want to drive with the tailgate down, both because I think it's unsafe in heavy traffic and because the thing flops up and down over bumps.

Thanks for your advice,

 

When I tried a few tanks with the gate up and a few tanks with the gate down on an older pickup a few years ago I couldn't measure any difference.

Mark

 

I have been told by some people at Ford that driving with the tail gate up is the most economic. It seems that Ford planned it that way. At the time the discussion was about the new body style 97+ and not the SuperDuty.

Regards

Jean Marc Chartier

 

as crazy as it may seem, i think JMC might be right. if you've ever riden in the back of a truck at highway speeds, you don't really feel any air turbulence which means that the air has yet to converge behind the truck(at least in my experience).

 

i did a project on this in a fluids lab that i did when i was a junior. taking the tailgate off actually increased the drag, since the back of the cab was a huge area of suction as the flow comes down off the top of the cab. when you have the tailgate installed, not much air flows down into the bed, so theres not as much of an adverse pressure gradient at the back fo the cab.... if you want to get better mileage, get a bed cover; this was by far the best, with tailgate up slightly better than no tailgate.... hope this helps.

also, your truck should be alot more rigid structurally with the tailgate up i would think.

 

That's absolutely right. You would think that the air would go over the cab and slam down into the bed, hit the tailgate and slow down the truck. In reality a "bubble" of high pressure air is created in the bed, all the other air rides over top making your truck nice and aerodynamic. It kind of creates laminar flow like you would find on some airplane wings.

-Jon

 

Hi Jm

I tend to agree with whats been posted here...however..

This is what i did...you might like to try the same...

Remove tailgate from bed...install one of those cheap nets...

Track your mpg...truck handling etc...for one full tank...

Reinstall tailgate(up & closed)...track mpg..etc..for one full tank...

You might be surprised at the results?

Sometime ago as i recall, reading the wind tunnel tests by Ford and others....seemed to be no real advantage with gate down..maybe even worse with it down...dont quote me on that!
I do remember none agreed with each other..

Can quote me on this....still see trucks with no tail gate but net..some with tail gate up... some down and the ones with no tail gate or net..well maybe thats why alot of stuff laying on. hiways.

Good luck...OT

 

I saw the aero testing on this...The best condition is with the fiberglas bed cover on...improved aero by almost 20%, next best was with the tailgate down, then with it up(which creates drag), the worst being without a tail gate..really bad flow this way...The tailgate down acts like a wing whereas the wind rolls off of it with some direction...