Ok, its time to sift through the wheat and chaff and find the facts. Over the years "they say" (whoever "they" are) that any Pickup will get better MPG by lowering the tailgate or removing it. I tried it several years ago with a 1500 350V8 4x4 and can't say that I realized any gain or loss. A buddy says that there was a wind-tunnel test done at some university and proved that the cab and box design inidicates that the vortex behind the tailgate was less than that of the cab, therefore the MPG would be better with the tailgate up rather than down. Well as usual, I could never find the details from the source. Now, I gotta admit that I am usually one of the biggest "Doubting Thomas's" around, so I am just trying to find the facts, not the BS. Does anyone on this list have statistical data to support or disprove the tailgate up/down factor? Or know where I can find it?

http://popularmechanics.com/automotive/auto_technology/2004/3/04_sae_congress/index5.phtml

I wonder how much that study cost someone? In the U.S. I am sure that would have been good for a few mil. on a grant. Maybe the air filter study that Spicer is working on could get some funding from a grant.

Thanks Max! The first time I pulled my 5th wheel with my 99 EC 6 1/2' box my rubber mat was lifting up high enough to smack the bottom of the trailer. I have the one in my Duramax screwed down. Later! Frank

Several years ago, Trailer Life , using both a Ford and Chevrolet with same driver ran the tailk gate up/down test( 500 miles each run) and determined there wasn't any appreciable difference. If I remember right they said the Ford actually got better milage with tailgate up but it was barely measurable. When I first went into pickups I wa one of those guys that beleived no tail agte gate better mileage so I took the tail gate off. . According to my driving habits and arithmetic there wasn't any difference. Now I leave the tailgate up except when pulling the 5th and then I take it off and leave it home.

http://popularmechanics.com/automotive/auto_technology/2004/3/04_sae_congress/index5.phtml


Darn... i guess it will take 400,000 miles then to pay for the bedcover thenhttp://www.dieselplace.com/forum/smileys/Ermm.gif

I wonder if in the test they considered the fact that the tailgate weights 45lbs, and around town it will need to be continuously accelerated and decelerated. For all we know, that test could have been at 80mph steady state, with no stop and go.


I remove my tailgate in the winter to keep the bed from filling with snow, and put it back in the spring. I have never noticed any gains or losses, but I like a lighter truck.

One thing to consider for those that run without the tailgate, If you run it enough and depending on the type of road you can end up having to repair the bed sides as they will break along the bottom at the bed.


I have seen this on several trucks over the years. Running with the tail gate closed supports the bed sides and keeps them from flopping back and forth.


Just some food for thought!


I always keep the gate up unless the situation prevents it.

We ran similar tests during my college engineering lab experiments in the mid '80s. We also found a few % improvement with the tailgate up on computer simulations, wind tunnel models, and real world testing. The combination of the tailgate vortex and the smaller vortex behind the cab due to the tailgate being up creates less drag than the larger vortex with the tailgate down.


Our best case senario was a bed cover covering at least the rear 1/3 or more of the bed along with a 12" "wing" extending from the top rear of the cab angling down ~10 degrees. This senario made about a 9% reduction in drag. There is not a lot you can do for a large gain since the frontal area is by far the largest factor in the drag calculation.


I run with it up!

It just goes to show, if a person has a question in this group, there is always someone here that can provide adaquate accurate information! Thanks

I went through the same thing, tail gate, no tail gate. Until someone mentioned that with the tailgate up you are providing support for your bedsides...no flexing. So I compromised and bought a louvered V gate. It's lighter and I can see what's behind me...no more backing over too-close Honda Civics....http://www.dieselplace.com/forum/smileys/HiHi.gif


JP

I think the strength of the tailgate sides would only be an issue when off-roading, or poorly maintained dirt roads. Of course I have not done any detailed testing, so others may know more.