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Interior & ExteriorDiscussions about the interior, and exterior of your vehicle.
This is a discussion thread titled "Mileage increase with tailgate off", within the Interior & Exterior forum, part of the Technical & Vehicle Assistance Forums category.
I removed my tailgate a couple months ago to help increase mileage with the ever increasing gas prices (2.07 here in the North Bay Area). I've kept mileage records since I bought my truck with 4 miles on it. My average mileage has increased from 15.4/17.2 (tailgate on) to 16.8/20.3 with my best trip being 22.4 mpg. My off-roading mileage increased from 14.4 average to 15.3 average. I average about 3500 miles/month of driving and have put 45000 miles on in 13 months now.
I just waxed the tailgate and stuck it in a corner of the garage, resting on an old towel. I didn't buy a rope or plastic net as the tailgate is easy to pop off or on. You may be able to get the same increase with the tailgate down, but I haven't tried this.
Hopefully doing the same will help someone out with the pain at the pump.
I agree, those increases in mileage are odd. This whole issue has been debated for years, and I also concluded that tailgate on/tailgate off didn't factor in when considering mileage. I think Click & Clack (Cartalk) talked about this at one time, and said they verified with their own tests that removing your tailgate doesn't improve mileage.
Had a '96 Dodge that I installed a cargo cover on. I had heard it made no difference and only did it to secure cargo when we traveled...but believe it or not, my mileage did improve slightly with the cover in place. Of course in the Dodge....a slight improvement still did not bring me up to 15 mpg!!!
Great looking truck but what a piece in terms of reliability.
I thought the same thing as Hockey Freak, but the weight still wouldn't make that much difference.
I think you were just driving slower making sure you didn't lose your cargo and were very easy on the gas to not let the cargo fly out the back.
I would guess the tailgate weighs around 75-100 pounds. I had mine off once to put the Trail Seal on and it was heavy but not heavy enough to make a difference.
Tests have been done and proven no noticeable effect with or without:
Air Gate
Tail Gate Up
Tail Gate Down
No Tail Gate
Soft Cover
Hard Cover
Full Shell
or whatever else.
Companies don't spend millions on wind tunnel test equipment to not know where the airflow goes. It simply goes over the tailgate.
__________________
1996 T100, 177,000 and counting
Be careful off-roading w/o the tailgate installed. The bed will flex alot more without the tailgate in place, and you could end up with wrinlkes in the sheetmetal. I've seen it before.
Having a canopy will cause a slight drop...but not all that bad.
At the dragstrip, the tailgate never made any real noticable difference for me, so I just left it on.
One of my co-workers has a nitrous-fed 350 in an S10, and it drops his time around two tenths with the tailgate flipped down. Of course, he's running mid-12s in that thing....at that speed everything counts.
Originally posted by hovisimo how'd it increase your offroading mileage? wind tunnel tests prove that putting the tailgate down gives no aerodynamic advantage over having it up. i drove with mine down for a while and noticed no improvement. i'd rather have the tailgate up... or on, in your case
I would like to see the source of the wind tunnel tests that you are referring to, because I find it hard to believe that the tailgate doesn't cause excess drag...no matter how much money has been spent on wind tunnel tests. That is the reason that your tailgate gathers more dust on the back than on the bed side. The tailgate is displacing air, creating a vacuum and bringing dust to the rear. It's the same principle as drafting a semi for improved gas mileage (for you, decreased for the semi).
I put the tailgate on when I have cargo in the back. As far as an improvement in off-roading, the improvement was noticed on graded forest service roads in the Stanisulas National Forest, at about 25-30 mph. Thanks John97 for the tip on sheet metal warpage w/ the tailgate off.
In Novato I saw regular for $2.27 at a Shell station...outrageous. I posted my personal observations and data on the hopes that it could help somone save $$ at the gas pump. It is working well for me. Take it or leave it, I really could care less.
Originally posted by Drago187 I would like to see the source of the wind tunnel tests that you are referring to
Do a search on the Internet, ALL the car companies have them and discuss them pretty openly.
Quote:
Originally posted by Drago187 That is the reason that your tailgate gathers more dust on the back than on the bed side. The tailgate is displacing air, creating a vacuum and bringing dust to the rear. [/b]
ALL vehicles do that regardless of tailgate or not, it is simple airflow. The back of any vehicle doesn't get any direct airflow therefore no airflow to "blow" the dirt away from it. Further more, most exhausts exit out the sides or the rear and that contributes to it largely. The exhaust has moisture in it allowing the dust to "stick" better once on the rear of the vehicle.
Quote:
Originally posted by Drago187 As far as an improvement in off-roading, the improvement was noticed on graded forest service roads in the Stanisulas National Forest, at about 25-30 mph.[/b]
You don't get "Gas Mileage" at 25-30 mph. You simply get "idle gallons per minute." At that speed, you could have a highway billboard in the box of your truck and not have it affect gas mileage that much.
I don't want to start any flames but I couldn't disagree more.
Opinions vary, and so do gas mileage!
__________________
1996 T100, 177,000 and counting
Just doing a quick search from Yahoo for "truck aerodynamics tailgate" I picked up a whole lot of responses. Ignoring the ones that were for companies advertising their products, there were a lot of articles that support leaving the tailgate up for better aerodynamics and safety.
One report did mention that adding a tonneau cover MAY help even more, and another noted that the net-gates actually could make it worse than just the open gate.
If it works for you, go for it. There's always variables that can change things.
__________________
Genthar
Rhino Lining, Waag one piece grille guard and wheel to wheel nerf bars, 3M Xpel on headlights, front corner lights, and foglights, Valentine One radar detector, XM Satellite radio, Lightforce 240 Blitz aux lights, Aux. reverse lights.
AEM Brute force intake, courtesy of AEM Power and TundraSolutions.com
Teamwest Coilovers, JBA Headers, Y-Pipe, and EVOL exhaust.
For less drag, keep tailgate up!
Excerpted from "Tom & Ray Magliozzi - The Car Guys" column in the Denver Post)
Dear Tom and Ray:
I read your recent article in which a reader (also named Kathy) asked whether a pickup truck gets better gas mileage with the tailgate up or down.
You guys said "down.".
My husband and I made a very large bet about the very same issue. I work for GM as an engineering intern and had a chance a couple of weeks ago to tour the design facilities in Detroit. When I got to the wind tunnel building, I asked the engineers this same question.
They laughed and demonstrated that trucks are designed so the airflow creates the least amount of drag when it flows off the roof and past the tailgate in the upright position.
They said that leaving the tailgate down would actually decrease a truck's fuel mileage. So guess who won the bet, guys?
Kathy
RAY: We know who won the bet, Kathy. because we received letters about this from engineers scattered throughout the automotive industry.
TOM: Here's one that offers a more technical explanation for you (still) nonbelievers.
Dear Tom and Ray:
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 automakers, and Lockheed was successful in convincing Ford, among others, that the wind tunnel wouId help them reduce drag and wind noise on their vehicles.
Needless to say, in the past 15 to 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 nonaerodynamc 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.
Ed Fitzgerald
Research Assistant
Department of Aero/Mechanical Engineering
University of Notre Dame
TOM: Sounds pretty convincing, Ed. Thanks. We also heard from none other than former GM President Bob Stempel, who wrote to say that aerodynamically it doesn't make that much difference. But, he says, a pickup truck is structurally much SAFER with the tailgate up.
RAY: So for that reason alone, we suggest you throw away those tailgate nets, folks. And as your flight attendant might say, please return your tailgate to the upright and locked position.
Originally posted by Drago187 I removed my tailgate a couple months ago to help increase mileage with the ever increasing gas prices (2.07 here in the North Bay Area). I've kept mileage records since I bought my truck with 4 miles on it. My average mileage has increased from 15.4/17.2 (tailgate on) to 16.8/20.3 with my best trip being 22.4 mpg. My off-roading mileage increased from 14.4 average to 15.3 average. I average about 3500 miles/month of driving and have put 45000 miles on in 13 months now.
I just waxed the tailgate and stuck it in a corner of the garage, resting on an old towel. I didn't buy a rope or plastic net as the tailgate is easy to pop off or on. You may be able to get the same increase with the tailgate down, but I haven't tried this.
Hopefully doing the same will help someone out with the pain at the pump.
Hi everyone, I'm no aerodynamicist or engineer so I do not undertstand how everyone calculates their MPG's. I mean, I would think you've got to use a complete tank of fuel on many occasions to come up with an average fuel consumption number. Is everyone running their trucks completely out of fuel or are you just running to half tank and multiplying by 2? In my Tundra 4WD, I get about 150 on the first half of the tank, and about 160~180 on the secong half. That's your typical southern california driving which is probably 65% or so freeway miles. On a recent trip to Mammoth Lakes I was able to to reach 215 miles on the first half tank. Does this mean my first half tank mileage (215 best) multiplied by 2 divideded by the tank capacity ( I'm guessing 23 to 25 gallons or so) 18.7 or 17.2 MPG AVG?
You can calculate gas mileage by filling up, resetting your trip odometer and driving around the block, then fill up again.
Gas mileage is simply how many miles you got per gallon of gas.
Ex. #1 Starting with a full tank and a reset trip odometer, you do your driving back and fourth to and from work throughout the week. You use approximately 3/4 of a tank. The weekend rolls around and you and the family want to go on a trip. You go to the gas station and fill up. First note how many miles it has been since you last filled up (trip odometer) ex 225 miles. You then get out and fill it, it takes 15.9 gallons to fill it. You take 225 miles divided by 15.9 gallons to equal 14.15 MPG.
Ex. #2 Starting with a full tank and a reset trip odometer, you leave the gas station full and drive around the block which puts .8 miles on your trip. Pull back in to the pump and put in .05 gallons of gas. You take the .8 miles divided by the .05 gallons again and equal 16 MPG on your trip around the block.
Get it? If not, maybe somebody else can better explain it.
*EDIT*
Bottom line is you must start with a full tank and reset trip odometer. Then it doesn't matter how far you drive. You can't run it empty and then put in $10 and expect to figure it accurately.
__________________
1996 T100, 177,000 and counting
Mileage increae with tailgate off
Well, you're on the right track...
Linear Mode
