Does a fiberglass tonneau actually decrease gas consumption?

[Saul]

Just wondering if tonneau covers really do help save on gas like the comanies suggest when they proclaim how "they pay for themselves" .. whay kinda gas savings have you noticed since installing a fiberglass cover on your truck?

As it looks right now I will have one late next week , it's used so I have to have it painted but I'm getting it pretty damn cheap! It's made by "Action" and is locking.

:mullet: :mullet:

[8banger]

Actually you are adding weight to your truck, probably around 100lbs. And from what i have heard the aerodynamic gains are minimal. You will most likely lose a little mileage.

Mythbusters did a show awhile back where they drove a truck with the tailgate down to see if it got better mileage through aerodynamics, and it actually lost MPG with the tailgate down, it was weird.

[Jasonb61]

I do believe a few other factors come into play such as actual body styling of the vehicle... I, for one, do not rely just on mythbusters.... its entertaining but how informative is it really? :biggthump

if you think about it, the air is going over the cab of the truck and then its trying to go back down into the space that was once occupied where the cab just passed.. as the truck moves, it would seem the air would hit the 90 degree (closed) tailgate and cause a little resistance wouldnt it?

But also, when the tailgate is down the air flows out the back of the bed very well... however, I believe it causes suction or a vacume on the front of the bed because it doesnt go STRAIGHT down after it goes over the cab... So I really dont know lol... But I heard different trucks are affected differently...

I think a bed cover is different than riding with the tailgate down... the cover should in THEORY achive better MPG by causing less drag... I try to visualize the airflow on the truck and I can't see how it cover would not make a difference for the better.. but im not aerodynamic scientist or whatever .. just trying to recall some of the stuff i heard while trying to sleep in science class :nana:

[SolidStateS15]

just get a soft tonneau for less weight and same effects. i don't really think i noticed any gains with it, but i'm sure it was good for a few mpg. mainly wanted it for the looks and to keep stuff dry. it's also easier when you do have to carry something big to just roll it up instead of having to take the whole thing off in 1 pc.

[ScojoDak]

here's the answer to the tailgate up/down, tonneau cover debate.

http://www.truck-bed-covers.com/Tonneau_covers_save_fuel.htm

[SmokinCummins]

I had 0 gain when I installed mine. I did it to keep stuff dry as well, not mileage. I don't run it anymore though - had to take it out to make room for my in bed fuel tank. :woot: :woot:

[dakota g33k]

i wasn't worried about mpg when i got my shell... more about preventing casual theft of cargo in the bed

[ucimaplaya2]

yeah the mythbusters thing was to show the difference in air flow with the tailgate up or down. What they found was that there was less resistance with the tailgate up. That DOES NOT mean that there is MORE resistance with a tonneau cover. Its two completely different paths of air flow. however you wont really see a major gain in fuel economy. I learned on a trip to tennesee that I gained 1 mpg economy on the highway over what I usually get. I hardly think that my tonneau cover is paying for itself, but it looks nice and keeps my stuff dry. Plus it weighs no more than 40lbs.

[8banger]

I don't see how adding weight to your truck can increase fuel economy, what I was saying was, the aerodynamic gains will probably not make up for the 50-100+ lbs you are adding.

[ucimaplaya2]

I don't see how adding weight to your truck can increase fuel economy, what I was saying was, the aerodynamic gains will probably not make up for the 50-100+ lbs you are adding.
its simple really. once the weight is moving, you are not applying as much work to keep it moving. so the added weight of a cover is nothing when in relation to the overall weight of the vehicle. Now if you were constantly accelerating there would be an increase of work and would make a huge difference. Now when you are cruising, you are constantly fighting drag at all times.

[dakota g33k]

i wouldn't say adding weight changes mpg as much as driving habits. i got 21 mpg cruising 70 mph between ozona and el paso with 1500 pounds of my stuff aboard.

[sick 660r]

I saw a gain of about 1.5 mpg when I installed my checkmate but it only weights about 40lbs

[slvdak]

I noticed a gain after I put mine on. It's a Mopar one and it doesn't way to much.
When the MythBusters did the test, they used a Ford Sport Trax, or whatever (I think). It was a four door with a 5 ft box. They contacted Ford and put a model of the truck in like a water wind tunnel. Within the bed, with the gate closed, it created like a vortec or something, which moved the new air over the back of the truck faster, but with the gate down, it put more drag on the truck.
As mentioned above, it depends on the trucks cab to bed ratio. I'm assuming that a Reg. Cab full size truck with an 8ft bed, would not produce a vortec the size of the bed, but then again, who knows.
I'm emailed MythBusters about it, and hopefully they will revisit the myth again.
:biggthump

[TurboBlew]

lol.... when gas is $3/gallon.... some places will say anything to sell you an over priced piece of fiberglass.

That being said.. you will see a small increase in mpg. I saw ~2mph more at the dragstrip with the tonneau on versus off.

Mythbusters...lol. Lets see them build a fast car or truck without that show's over blown budget...that would impress me. :nana:

[burningrubber01]

umm im just applying my little knoledge of aircrafts here, as u know the skins over aircraft wings are riveted to the wing's frame , these bunch of little rivets were causing alot un neccesary parasitic drag so one guy had the idea to counter sink the rivets and smooth the wing down... needless to say the top speed of the plane gained by a few mph

[burningrubber01]

just a thought i mean if anything is sticking out off the main body of the truck there will be parasitic drag and therefore will slow u down. i woulnd be surised if there was a deacrease in consumption but nothing that would cover the expense of the tonneau, or anything too significant

[davensj]

Myth Busters tested this once, Tonneaus on and off, Tailgate up and down.
And if i remember right they used a Dakota too, and got NO gain in gas mileage either way.

[TurboBlew]

Mythbusters did a show awhile back where they drove a truck with the tailgate down to see if it got better mileage through aerodynamics, and it actually lost MPG with the tailgate down, it was weird.

lets agree in the future you will NOT quote mythbusters as a factual entity...ok?? Otherwise youll get negative rep!!!!!!!!!!!!!:bump:

[TurboBlew]

Myth Busters tested this once, Tonneaus on and off, Tailgate up and down.
And if i remember right they used a Dakota too, and got NO gain in gas mileage either way.

lets agree in the future you will NOT quote mythbusters as a factual entity...ok?? Otherwise youll get negative rep!!!!!!!!!!!!!:bump:

[70Cuda383]

Everyone uses fuel economy as a selling point for their product. Keisler was using "fuel mileage" as a selling point for their 5 spd conversions for muscle cars, saying that with the OD trans, your highway RPMs drop enough that if you drive like, 3500 miles a year, the trans will pay for itself in 6 or 7 years:jester:

whatever.


it might be true, but who drives a muscle car on the highway at 70mph for hours on end? unless you are driving it to a national level show, 90% of the time they are being driven on country roads, city streets, etc. where they will hardly see extended periods of an even 70MPH speed.

If you buy a tornado at the same time and put it on with your new bed cover, you'll get like 48MPG from your 4.7L dakota*

















































*48MPG was achieved in a real world test, with the engine off, coasting behind a semi, while coming down the east side of the continental divide and a 65MPH tail wind.

[Fluffy]

Read the dates before posting. :facepalm: :jester:

[70Cuda383]

Read the dates before posting. :facepalm: :jester:

Read this:


shut the fuck up.

[TurboBlew]

Read the dates before posting. :facepalm: :jester:

I was in after the thread revival....lol :stirthepo

[hskrRT]

Myth Busters tested this once, Tonneaus on and off, Tailgate up and down.
And if i remember right they used a Dakota too, and got NO gain in gas mileage either way.

You remember wrong. The tailgate up and tonneau numbers were almost identical with a small nod to the tonneau, but the tailgate down numbers were worse. They didn't do the whole top off with gas, drive, top off with gas thing. They hooked up some sort of fuel flow meter to track the amount of fuel flow. More fuel flow, more gas consumption, less gas mileage. It was a Dakota though. Pretty sure they said the difference between tailgate up and tonneau on wasn't enough to confirm the myth, but there was a small difference. They said it was so small that most people wouldn't notice the difference in the normal gas mileage calculations.

Now, aside from the gas mileage thing, it is just so much nicer to be able to lock stuff up in my bed under the tonneau and not worry about it getting stolen or exposed to the elements.

[87 dakota]

Actualy, You're BOTH wrong. Tailgate up; baseline, tailgate down; worse, tonneu, SLIGHT improvement. Yes, a tonneu adds wieght, about 50 lbs. No, that is not enough wieght to significantly affect gas milage on a vehicle that already wieghs 3500 lbs or more and is geared more for towing/ hauling than outright fuel economy. Tailgate down is worse b/c aerodynamic drag, tonneu is better b/c aerodynamic drag. Don't remember his name right now, but a very famous stock car driver used to prefer station wagons over sedans for this very reason, in spite of the fact that a wagon typicaly wieghs about 200 POUNDS more than a sedan. in a long race, aerodynamics is better than light weight. Also on long drives. hskRT got it right

[ScojoDak]

Maybe this configuration will help....

http://itsracingtime.com/wp-content/uploads/2009/04/img008671.jpg

[87 dakota]

:funny::funny::funny::funny::funny:I don't care who you are that's funny right there

[Dennis F]

On the highway driving 140 miles a day, I picked up a solid 30 more miles per tank. I did this back to back plenty of times be removing the cover and putting it back on. It was a consistent 30 miles using my trip meter divided by gallons to fill back up.

I have a ARE cover.

[DakFink]

On the highway driving 140 miles a day, I picked up a solid 30 more miles per tank. I did this back to back plenty of times be removing the cover and putting it back on. It was a consistent 30 miles using my trip meter divided by gallons to fill back up.

I have a ARE cover.

You're probably one of the very few that would actually see and/or benefit from a Tonneau saving Gas. Around Town and short 10-20-30 mile trips here & there? Forget it!! It would be marginal at best.

Just like everything I ever read about Putting 24.5" rims and Semi tires on my 3500. Everyone under the sun would argue one way or the other. Same issues, Drag, Weight, Load, Size etc.

Heres the facts: I had the Speedo Calibrated when they were installed so I knew that it was correct on speed and Milage. I drove from Killeen Texas to Miami Florida @70MPH, getting 18MPG. After they installed the Wheels, Tires and calibrations I got 22MPG all the way back to Killeen from Miami. Even double checked this using GPS and MapQuest for secondary references.

I also picked up the same around town. 14mpg to 18mpg this is in a Quadcab Diesel.

You're not going to be so lucky with a gas engine. If you see 3-4 on the highway you'll be lucky to see anything around town. maybe 1-2mpg.

[Dennis F]

Around town I notice no improvement.

But my commute at the time was 70 miles each way, 67 was all highway and there was a definite increase in mileage. This was traveling at 65 mph 99% of the time, not going 80.

Although the truck did feel a tad bit more stable at higher speeds after the install.

Of course, your mileage may vary:quoties:

[BlakDakRT]

i know on my ram it picked up 1 mpg not sure it will be same for dakota but in my opinion the gas mileage is just a plus.. they look better and get lil better gas mileage.. win win situation

[capt1972]

why does the craftsman truck series run a simmulated tonneau on all their trucks? hmmmm:huh::stirthepo

[hskrRT]

Because if they didn't, then they wouldn't be ablee to get the airflow over the rear spoiler for the donwforce they need.

[AllThingsEnd]

why does the craftsman truck series run a simmulated tonneau on all their trucks? hmmmm:huh::stirthepo

Because if they didnt you wouldnt have to dig up an old ass thread which was already dug up once before.

[threesixoh]

re-necrofied!

[ThisOldDak]

aerodynamics has as much to do with pressure differentials as it does with disturbing the flow. 2 sides to the same coin but different ways to approach it.

With the gate up it will catch some air, but will keep the pressure just behind the cab a little bit higher. Thus reducing the pressure difference in front of the cab and behind it. Then the air can more smoothly pass the cab and gate.

In theory a cover would gain you some highway mpg (maybe .5mpg). but you also haveto accelerate to that speed, where the added weight comes to play. A change in driving habits would be necessary (less stopping IE tailgating) but you would also see big gains by doing this without the cover. So that's why they say the best thing for mpg IS just to change your driving habits.

I notice a big difference with the cover on mine. It seems so much more peppy without it and the extra weight. but I like having a giant trunk

[burningrubber01]

lol revived i pulled 20 mpg's with my truck on a 60 mile trip doing 65-70 most of the way and it wasnt even all highway

[ConkerandDakota]

yeah i had a cap on my truck and i wish i did for what happen a while ago, had some stuff in the bed (not very important but needed them a couple days ago) but went in the store for about 5 minutes got what i went to get, didnt notice it til a couple days later but someone stole it outta the truck

[ConkerandDakota]

lol revived i pulled 20 mpg's with my truck on a 60 mile trip doing 65-70 most of the way and it wasnt even all highway
with the cover on? mine... i dont have anything covering the bed and was getting 21mpg doing about 60-80 went from 70 to 55 cause of a cop once, but still got the 21 per gallon

[Bad Sport]

aerodynamics has as much to do with pressure differentials as it does with disturbing the flow. 2 sides to the same coin but different ways to approach it.

With the gate up it will catch some air, but will keep the pressure just behind the cab a little bit higher. Thus reducing the pressure difference in front of the cab and behind it. Then the air can more smoothly pass the cab and gate.

In theory a cover would gain you some highway mpg (maybe .5mpg). but you also haveto accelerate to that speed, where the added weight comes to play. A change in driving habits would be necessary (less stopping IE tailgating) but you would also see big gains by doing this without the cover. So that's why they say the best thing for mpg IS just to change your driving habits.

I notice a big difference with the cover on mine. It seems so much more peppy without it and the extra weight. but I like having a giant trunk

I disagree with that statement. It's been proven that drafting improves fuel economy. Just watch Myth Busters and see how much their fuel economy increased following 12" behind a 18 wheeler! :jester:

[hskrRT]

Pretty sure at 12" they actually had an increase in gas consumption. The best overall distance was like 4' or something like that.

[Bad Sport]

Pretty sure at 12" they actually had an increase in gas consumption. The best overall distance was like 4' or something like that.

I was just being sacastic. After reading the thread I had to put Mythbusters and a Nascar term in the same post.

[ThisOldDak]

I mean tailgating as in those folks who are on the ass of anyone they are behind and on the brakes 50% of the time because the person infront of them isn't going a perfectly constant speed. I'm sure everyone sees this daily, unless this is just a crappy ohio driver thing. eheh

[dakotanut]

Why don't yall do a comparison test on your trucks and see instead of arguing about it. Each truck is different. I don't give a shit about gas mileage. It could get 1 mile to a gallon, I don't care. I do care however, about the thousands of dollars in tools I carry in the bed of my truck. If that gets stolen then I'm screwed. I would like to have one just to keep my stuff safe.

[Deez]

Didnt read everybodys posts but Mythbusters did a test on this and it did not save any gas

[dakotanut]

I don't have a bed cover. I plan on getting one very soon. I know what my gas mileage is now. I will drive a few tanks and see what happens. The thing is that I'm gonna get new tires also. So that may change it. Plus, since my compressor for my a.c. won't turn off when I step on the gas, I am taking it easy for now.

[Baxter02]

Hey guys, I think Mythbusters did a show about this once...









Wait a minute.

[Rob454]

i didn't lose anything but I didn't gain anything. i got it more for the ability of keeping my tools safe and dry and also the tailgate couldn't be opened without first breaking onto the tonneau cover

[hotrodbob38]

Mythbusters says no..
But I like to lock my stuff up out of site..
And it looks much better .. ARE fiberglass..

[DakRat33]

When I got my cover about 6mos ago I did notice an increase in MPG. I had to drive to SoCal to get it, then drive back w/it installed. I did noticed an 1-1.5 mpg increase with it on. And that was about a 700-800 mi round trip.

[96BlkDak]

talk about a thread that wont die


here is my $.02

my 99 F150 i got 1-2mpg better on the highway with it than with out it.

[Adobedude]

talk about a thread that wont die


here is my $.02

my 99 F150 i got 1-2mpg better on the highway with it than with out it.

I think this was on Mythbusters once :funny::funny::funny:

[9t9-5.2]

I think this was on Mythbusters once :funny::funny::funny:

Wasn't the Myth Busters tail gate up or down?
I may be wrong.

[jfl1960]

Can't say for sure about the gas mileage saving but my tonneau has saved me hundreds in preventing theft, I have had several tires and rims stolen out of other trucks I have owned, even after running a chain through the tire rim combo and chaining them around the light bar/roll bar, they were stolen just because they were in plain sight, have left everything from my luggage, tires, computers, etc... in my truck since the new tonneau and nothing has been touched, I did add a locking mechanism to the tailgate and recently upgraded to the fiberglass tonneau.

Plus it keeps my stuff dry and looks great. Don't buy stuff for the hype a salesman will give you, buy it for it's practical application and if there's a gain in another area then that's a bonus for you. Trust me I'm a salesman.

[02sxtkota]

i just like having my soft cover on for looks and i can put shit back there to keep dry and just rolls up when need to and fiber glass cant exactly take off when u buy a new fridge in one of those spur of the moment things.

[hskrRT]

I don't think I'd ever call a fridge a "spur of the moment" buy. lol And I have a trailer to haul stuff with so I don't have to remove my tonneau.

[02sxtkota]

I don't think I'd ever call a fridge a "spur of the moment" buy. lol And I have a trailer to haul stuff with so I don't have to remove my tonneau.

it was cheap and needed new one so i just grabbed it cause it had a dent on the back which i didnt care cause who sees the back.

[TurboBlew]

Mythbusters says no..
But I like to lock my stuff up out of site..
And it looks much better .. ARE fiberglass..

you should cite Mythbusters where ever you go!
It makes you seem smart!:bump:

[jfl1960]

Just did a return trip from Sydney NS, Canada to Halifax NS Canada and back to pick up my fiberglass tonneau for my truck, paid $100.00 for the tonneau and got a chance to visit with my nephew and his wife and see newborn baby they just had, it is approx 400 KMs one way, didn't think to record the exact mileage and do the MPG calculations but it took a full tank to get there(was well below the red warning on the fuel gage) without a tonneau and returned with Fiberglass tonnea on truck only took a little over 3/4 tank, windy as f*ck on return trip today too, so I think it helps.

[jfl1960]

As for the inconvenience of having to remove a cover to carry something in the bed, I have found that even the soft tonneau is a pain in the ass, however it is a one man job for the soft cover but a two man job for the hard shell and the hardshell must be done at home so you can store the cover properly, maybe having the hardshell will stop the impulse spending you have, might keep some cash in the bank, lol, really a new fridge is never an impulse at least not with my wife, that would be a 6 month search for the right color, fit, option, etc..., and then it would be delivered and installed by the seller because my wife wants it done immediately, while I pay for it.
It's all a choice of preference, as far as I am concerned, they are both a pain but I like the look, I like my luggage and tools being dry and secure and I do think it helps on mileage. Good luck in whatever you decide.

[87 dakota]

you should cite Mythbusters where ever you go!
It makes you seem smart!:bump:

Actualy Mythbusters DID find a slight improvement with a tonneau, abou what some are saying here. It was TAILGATE DOWN that showed no improvement

[TurboBlew]

Actualy Mythbusters DID find a slight improvement with a tonneau, abou what some are saying here. It was TAILGATE DOWN that showed no improvement

mythbusters is a tv show designed to entertain and sell ad air time.
It worries me that people actually "believe" any of their conclusions.

[87 dakota]

Didn't actualy need Mythbusters to test this, any slightest understanding of aerodynamics will lead to the same conclusion. Not to mention the people who've actualy put a tonny on and seen their numbers improve.:D

[BlueDragon]

I gained 2 MPG on my 05 Quadcab when I had my Leer installed.