tailgate down: better mpg?

[Hawaii50]

will leaving the tailgate down really give better mpg? i've tried it and i dont know if there's any significant difference if any. and hey...there are no stupid questions

[crazymjb]

You actually get better mileage with the tailgate up. See: Mythbusters

 

Basically, with the tailgate up the air creates a "bubble" if you will in the bed which the passing air flows over, while when it is down it drags allong the bed.

 

Mike

[95Sierra2500]

You actually get better mileage with the tailgate up. See: Mythbusters

 

Basically, with the tailgate up the air creates a "bubble" if you will in the bed which the passing air flows over, while when it is down it drags allong the bed.

 

Mike

 

<{POST_SNAPBACK}>

 

 

 

This is only true of short-box trucks. Long box trucks, the tailgate works against you and lowering it actually can help. Since most trucks are short-box anymore (people buy trucks to ride around in, not use like trucks), they tested only a short-box truck on Mythbusters.

 

That being said, the difference is actually not very much (like .5mpg).

[Sierra 05]

You actually get better mileage with the tailgate up. See: Mythbusters

 

Basically, with the tailgate up the air creates a "bubble" if you will in the bed which the passing air flows over, while when it is down it drags allong the bed.

 

Mike

 

<{POST_SNAPBACK}>

 

 

I second that!!!!!!!!!!

Saw that episode also. That was interesting.

Keep the tailgate up.

[Hawaii50]

thanks! yea, i knew it was all in my head

[redvett]

Long box or short it does no makea difference. Go here for the GM test.

http://sitemaker.umich.edu/um.gm.truck

And this should convince you if nothing else.

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.

Ed Fitzgerald, Research Assistant, Dept. of Aero/Mechanical

Engineering, U. of Notre Dame

[OUMike]

Long box or short it does no makea difference. Go here for the GM test.

http://sitemaker.umich.edu/um.gm.truck

And this should convince you if nothing else.

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.

Ed Fitzgerald, Research Assistant, Dept. of Aero/Mechanical

Engineering, U. of Notre Dame

 

<{POST_SNAPBACK}>

 

 

 

Yup....exactly what Jamie and Adam said. I love Mythbusters.

 

Notre Dame eh.....think they'll be any good?

[crazymjb]

They did do a "fluid" test too.

 

Now what about taneou(sp?) covers which claim to improve mileage?

 

Mike

[OUMike]

They did do a "fluid" test too.

 

Now what about taneou(sp?) covers which claim to improve mileage?

 

Mike

 

<{POST_SNAPBACK}>

 

 

 

I'd think those too would hinder mileage. Seems like the flat surface would "burst the bubble" as well. Definatly be interested to see some results.

[gmcjoe]

Long box or short it does no makea difference.

 

Correct

[asilverblazer]

Tonneau cover replaces the air bubble with a real flat surface for the air to go over. It is the best solution.

[Skylane]

I've seen four instances (me being one), where the truck hit a bump, the tailgate bounced up and came off the hinges. This is not a good thing.

If one of the wires that keeps the tailgate from going all the way down when open, comes off, the tailgate will fly around like crazy on the remaining wire.

This can become pretty interesting at freeway speeds!

I've also been advised by a Calif Hwy Patrolman that a tailgate in the down position, with nothing to keep it from bouncing up could be considered an unsafe load.

[sc4808]

It also bears mentioning that the tailgate also serves as support for the bed, if you ride around too long with the tailgate down or removed, the sides of the bed will loosen and eventually start flappin in the breeze.

[redvett]

Here is a little info on tailgate down.

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.

Ed Fitzgerald, Research Assistant, Dept. of Aero/Mechanical

Engineering, U. of Notre Dame

[uh6077]

Keep the tailgate up. There are many reasons to keep it up and only one unproven reason to keep it down. Think of it this way. The auto makers have to keep the mpg as high as possible for the entire line of vehivle or else pay high penalties. If they thought they could get better gas mileage with the gate down, they would make a gate that allowed the wind to pass through. Having the gate down can ruin the gate, makes lots of noise, someone can drive into it at a light, looks stupid, and hurts mpg. This is a no brainer. Please don't be a complete redneck and use one of the nylon strap style gates.