[ThugNasty]

Ok I always hear people arguing over whether leaving the tailgate down or up or taking the tailgate off will increase or decrease MPGs.

So, I decided to conduct my own tests. Since I bought the Truck back in February I've been calculating MPG at every fill up and averaged them together.
Here's what I got:

With tailgate up: 16
Tailgate down: 16
Without Tailgate: 19

 

[colin123]

there are so many other variables effecting it in a real world test that its virtually impossible to get viable results like this because aerodynamically speaking it is a scientifically tested and proven fact that having it down or off will raise your vehicles drag therefor lowing your fuel efficiency. the tailgate is crucial to creating the airflow needed to have the smoothest airflow and smallest possible wake at the back of the truck. the problem with doing real world tests is that it adds too many real world variables to get a true result with something like this. to prove that look at your results. going from tailgate up to down obviously makes an aerodynamic change which one way or the other will result in a change in efficiency so a change should have been seen there and would have in a controlled test, and also taking your tailgate completely off as opposed to it being down would not make enough aerodynamic changes to boost your mpg up by 3 even with the slight change in vehicle weight. i don't know how you felt about the results and i hope i'm not bursting your bubble about it but thats pretty much how it is.

 

[truckchick78]

Mythbusters did the same test and had the results you are talking about. The MPG was worse with the tailgate down.

 

[ThugNasty]

I realize that there are too many real world variables that could affect a real world test and I realize that 19 is a little drastic, after all it is a real world test.

Wind tunnel testing has predominantly been on trucks with a bed length of 6 ft or more which rules out most compact trucks. such a short bed on a truck does not form as much of this "air bubble" of wind behind the cab like larger trucks do.

Also according to weight the tailgate of our Frontiers is very heavy, If most of your driving was at low speeds where aerodynamics were not a significant issue the reduction in weight would help a little.

There is also a lot of debate over tonneau covers about this.

Mythbusters did the same test and had the results you are talking about. The MPG was worse with the tailgate down.

And then mythbusters went back and retested it with a more accurate setup:

YouTube - Insert from MythBusters - Tailgate Up or Down 2 (from More Myths Revisited) fuel consumption test

 

[SDFrontier85]

On my 4 banger, I already get 20 city with it up and on so I'll just keep on keepin' on.

 

[SDFrontier85]

And then mythbusters went back and retested it with a more accurate setup:

YouTube - Insert from MythBusters - Tailgate Up or Down 2 (from More Myths Revisited) fuel consumption test

Is there something wrong with his truck or something? 11MPG on the freeway? I still don't think his test is accurate if he's getting that kind of mileage or lack there of. lol

 

[colin123]

Tailgate Up or Down

if it was better to run with it down on any vehicle then the epa would be telling us to and trucks would be designed this way, "ease on the accelerator", "keep tires properly inflated" blah blah blah. when doing epa testing on vehicles manufactures do anything they can to get the best possible mpg to get a good epa rating even though we all know its next to impossible to consistently get those sticker numbers. its simple aerodynamics regardless of the size of the truck its still the same

 

[colin123]

Ed Fitzgerald, Research Assistant, Dept. of Aero/Mechanical Engineering, U. of Notre Dame

"I'm an aerodynamics engineer. When I was in the U.S. Air Force a few years back, I worked with folks from the Lockheed low-speed wind tunnel. In the 1970s, aircraft production went into a slump, and Lockheed started looking for other customers for its wind-tunnel services. Prime candidates were the auto makers, and Lockheed was successful in convincing Ford, among others, that the wind tunnel would help them reduce drag and wind noise on their vehicles. Needless to say, in the past 15-20 years, Lockheed has learned a lot about car and truck aerodynamics. Anyway, they actually performed drag tests on pickups with the tailgate both up and down, and found that drag was actually LOWER with the tailgate CLOSED! This ran counter to their intuition (and yours). The reason is that a closed tailgate sets up a large "bubble" of stagnant air that slowly circulates around the bed of the truck (we aero types call this a "separated bubble"). When air approaches the truck, it "sees" the bubble as part of the truck. So to the air, the truck looks like it has a nice, flat covering over the bed, and the air doesn't "slam" into the vertical tailgate. If the tailgate is open, or replaced by one of those "air gate" nets, however, that nice, separate bubble in the truck bed does not form (it "bursts"). Then the air approaching the truck "sees" a truck with a flat bed on the back of a tall cab. This is a very nonaerodynamic shape with a very LARGE drag. So, believe it or not, it's best for gas mileage to keep the tailgate CLOSED. Hope this information is helpful".

 

[Mylt1]

Tailgate Up or Down

if it was better to run with it down on any vehicle then the epa would be telling us to and trucks would be designed this way, "ease on the accelerator", "keep tires properly inflated" blah blah blah. when doing epa testing on vehicles manufactures do anything they can to get the best possible mpg to get a good epa rating even though we all know its next to impossible to consistently get those sticker numbers. its simple aerodynamics regardless of the size of the truck its still the same

actually, up until a year ago(i believe thats when the new EPA test started) there was no actual driving of the cars. all they did was put a "sniffer" in the tail pipe and run it on a dyno type device and measured the gases coming out of the tail pipe. thats how they figured out the EPA "estimated" MPG. a LOT of people complained about the EPA'a rating being WAAAAAY off so the EPA was pressured to reevaluate there test. after that they said they would actually "road test" cars instead of the sniffer. i cant say 100% that the new test have take over yet though.

 

[colin123]

thanks for the correction on that. this still does not change that this issue is not debated by car manufactures or the scientific community the only people that still debate it is the general population when its really a non debate issue. the controlled tests have been done, many many of them and the results have all came to one conclusion. up is the way to go.

 

[nissanmadness]

actually, up until a year ago(i believe thats when the new EPA test started) there was no actual driving of the cars. all they did was put a "sniffer" in the tail pipe and run it on a dyno type device and measured the gases coming out of the tail pipe. thats how they figured out the EPA "estimated" MPG. a LOT of people complained about the EPA'a rating being WAAAAAY off so the EPA was pressured to reevaluate there test. after that they said they would actually "road test" cars instead of the sniffer. i cant say 100% that the new test have take over yet though.

^+1 It's about time they finally get off their duff's, and actually, "DO", something for a living!

 

[ThugNasty]

To each his own opinion...

Regardless to what the experts say I still take my tailgate off for long trips and consistently get better gas mileage.

 

[SDFrontier85]

To each his own opinion...

Regardless to what the experts say I still take my tailgate off for long trips and consistently get better gas mileage.

So there's no chance that you're getting better mileage because you're (I'm guessing) doing highway or non stop/go driving on a long trip?

 

[bensfrontier]

Let's not forget that the tailgate adds structural stability to the bed of the truck. Without the tailgate, the bed rails would get flimsy over time.

 

[ThugNasty]

So there's no chance that you're getting better mileage because you're (I'm guessing) doing highway or non stop/go driving on a long trip?

Better gas mileage than I would if I had left it on.


As for structural rigidity the tailgate adds nothing, its only held on by two small locking mechanisms that are engaged when the tailgate is up.

I do keep my tailgate on the majority of the time to keep my stuff in my bed when I'm hauling. The sole purpose of a tailgate is to keep stuff in the bed.

 

[colin123]

i really find it funny how much people are so skeptical on the scientific data and wind tunnel tests of this subject. its not really a to each his own opinion type thing its a yes or no thing that has been wind tunnel tested and is agreed on by automakers and scientists alike and something that trucks are aerodynamically built around if you read what the auto makers say about it. saying to each his own everyone has an opinion about it is like saying to each his own everyone has an opinion weather sunscreen lowers the effects of uv radiation from the sun on a person. it either does or doesn't and has been tested to show it does. i'm not trying to be a d bag but thats just how it is.

 

[chaz]

bed cover,my mpg went up from 17.5 to 17.6,thats all i can say i have also tried everything he has gate on /off etc.
its a truck that drives like a car that eats gas like a truck.

 

[FitzIngarage]

Let's not forget that the tailgate adds structural stability to the bed of the truck. ...

I've read this too. If you get rear ended, the heavy tailgate can help protect cabin occupants from intrusion and if hit on the side, can help keep the body panels squared and better able to absorb impact.

To each their own, I guess. I keep my tailgate on and up, unless I'm using the bed extender for extra hauling capacity.

 

[OkieScot]

I don't know if the tailgate strengthens the integrity of the truck when it is latched, but My common sense tells me that it does. I had a 1977 Datsun KC 5 speed and when you latched that tail gate you could actually see the sides of the bed move inward as you pulled the latches to lock them.

The same is said for the doors of a vehicle adding to the integrity of the vehicle when they are latched.

 

[Zero Six LE]

There is a guy in my subdivison that drives his F150 w/o the tailgate all of the time. I guess he's convinced he gets better fuel economy that way.