Hey guys, i was just watching the discovery channel this afternoon and was watching mythbusters... if you guys arnt familair with it.. its a show with a bunch of guys that scientifically test old myths to find out if they are true or not... well they tested the MPG gain ofr loss withe driving with your tailgate down or up.. they used 2 identical brandnew f150's and started out with a full tank and drove together on the identical route at the same speed... one with the gate down and one with the gate up... and they were seeing witch one ran out of gas first. and surprisingly the truck with the gate down ran out of gas first.. obviously showing that driving with your tailgate down hurts your mpg then helping it. really interesting.. they also did a water tank with a scaled down model test and it showed why it works..really intersting.

 

Mythbusters is great edutainment.
I just posted the water tank video clip from that episode.
2.81 MB

https://dodgeforum.com/m_330502/mpag.../tm.htm#330502

https://dodgeforum.com/forceddownload.asp?file=0;330502

 

I imagine it would depend up on the truck and its individual aerodynamics.
I used to pick up about 1.5 MPG in my old 2.9L Ranger with the gate down and/or off.

 

im sure it changes from truck to truck but the proof is there.. its a myth

 

Throttle body spacers are also a common fuel saving myth...as well as high octane fuel (used in vehicles not setup for it).

 

Yea i watch that show today, I wonder if my toolbox in the bed is traping the air.

 

Plus you dont have to chase your tool box down the road when it falls out for no tailgate. Just proves, bed covers do more for saving fuel then tailgate down.

 

I think the bed cover thing is a bit overrated too, I never saw any benifit in mpg from mine. but mine also weighs over 100 lbs which is probably why. I though of making a custom cover that would fit down into the bed and be flush with the top of the bed but it'll probably never happen. it wouldnt be water tight of course but that wasnt the idea behind it anyway.

the test with the trucks, I dont buy their methods... what they need to do is to drive 1 truck for 100 mile route once with the gate up and once with the gate down and trying to maintain the same speed on each trip and measure the mpg each trip. that will tell you if there is a difference with the gate up or down. having 2 trucks only works if you can prove both trucks get the same gas milage prior to the test.

If I can remember, once I get back from the holiday, I'll pull my cover off and run my test on it, although it's only 35.4 miles, it's a reliable route without much traffic (on the weekends) and it's all freeway.

 

steve... they were identical f150's off the showroom floor.. no miles on either... they mpg between the 2 cant be soo far off to cause the truck with the gate down to run out 40 miles before the truck witht he gate up.. i see what your sayin though.. it would be optiumum conditions to use the same truck and just do a shorter trip.

 

well, with my 01 Dakota, I got better mpg with my fiberglass bedcover then I did without it. I'd average 16 without it, close to 20 with it.

That only applied to long trips though, not in the city driving.