Tonneau Covers And Fuel Economy

Col_Sanders · February 1, 2010

Anyone notice any improvements in mpg with a tonneau? I know the 10% many of them claim is more than likely an exaggeration, but is there any gain at all? I just installed mine and will be checking on this tank but I think my results will be inconclusive. My DIC has been reading 17-18.5mpg for the past 4 tanks.

Matt_ · February 1, 2010

if it does change it, its not going to make a big enough difference to show up in your calculations.

if anyone buys a tonneau cover solely to "get better mpg"... they should be slapped like a biatch for stupidity.

Stevens03 · February 1, 2010

if it does change it, its not going to make a big enough difference to show up in your calculations.

if anyone buys a tonneau cover solely to "get better mpg"... they should be slapped like a biatch for stupidity.

Agreed.. It should be done to keep stuff dry, but not mileage

66nova · February 1, 2010

Mythbusters has actually tested this on two different occasions and actually got worse gas mileage with a cover. It has to do with a vortex of air that is created by the bed/tail gate that allows most of the air to glide over the top of the truck. They also found that driving with the tailgate down did not yield better mileage.

So a big +1 to what has been said above. Buy a cover for keeping cargo dry.

I have had a cover on both of my last two trucks and never got any better mileage.

jro909 · February 1, 2010

it was myth busted..along with driving on the highway with the tailgate down...it dosen't do anything for mileage, the cab and the height of the truck is what causes the drag which turns into more fuel consumtion

Col_Sanders · February 1, 2010

Dogs take up the whole backseat and I need a place to put my luggage that could keep it dry. I was just curious if their claims had any truth to them.

xaugievike · February 2, 2010

I've had 3 trucks with covers:

1st was a dodge dakota - got a solid and consistent 1mpg improvement with it

2nd - Nissan Titan - zero to negligible difference

3rd - My bowtie - zero to negligible difference

What I really got them for is to make the bed a bit more weather resistant when using it as a "trunk." but i love that the soft cover can be quickly rolled up for hauling bigger/dirtier gear.

drbob11 · February 19, 2010

i have an 09 sierra 1500 and put the bak-flip G2 on mine and i got maybe 1 mpg better so far. the bak flip is the hard cover that folds back. it is awesome, keeps items safe and keeps things dry in the bed plus it locks. personally, i think there are so variables to consider in each persons case relating to mpg's ie: drive style, rearend gearing, carry extra crap in the truck etc.. to really get a good evaluation of ones mpg's. drive style really makes the difference. my friend installed the bullydog "watch dog" program and he jumped almost 5 mpgs by just driving per the units guidance system. he didnt add anything to his truck except the programmer. hope that helps out some.

Col_Sanders · February 20, 2010

I added a leveling kit, K&N, and 33s right after the tonneau, so my numbers are useless. However, after all that I am down about 1.5mpg (18 to 16.5) but it has been colder so that could be affecting it.

drbob11 · February 20, 2010

hey col sanders! i want to do exactly what you did to your truck.. CAI level kit and tonneau... i am part way there. i added cover and CAI just need the level kit and taller tires. do you have any before and after pictures you can share? i have been looking for someone that has the same truck and did the same mods.

emejay · February 26, 2010

I just got a Truxedo Lo Pro last month, and I can absolutely assure you it improves mileage, about 1 MPG in my case where I do lots of highway driving. If most of your driving is as low speeds or city, don't expect much. I have found the engine is in V4 much more with the cover installed.

With the Hybrid Sierra, GM made only 2 aerodynamic changes to increase fuel mileage. One was a tonneau cover, the other was changing the front air lip to one which is 11 mm lower. This fact convinced me to try a cover, and my experience has been positive. It also is great to hide stuff and keep it from blowing away.

Col_Sanders · February 26, 2010

hey col sanders! i want to do exactly what you did to your truck.. CAI level kit and tonneau... i am part way there. i added cover and CAI just need the level kit and taller tires. do you have any before and after pictures you can share? i have been looking for someone that has the same truck and did the same mods.

I'll try to get some up Monday. I have only taken 1 since I did the mods and it was a crap cell phone pic. I wont have interweb this weekend and the boat is hooked up now so its sitting a little low.

Sierra in the Sand · March 19, 2010

Mythbusters has actually tested this on two different occasions and actually got worse gas mileage with a cover. It has to do with a vortex of air that is created by the bed/tail gate that allows most of the air to glide over the top of the truck. They also found that driving with the tailgate down did not yield better mileage.

So a big +1 to what has been said above. Buy a cover for keeping cargo dry.

I have had a cover on both of my last two trucks and never got any better mileage.

I saw that Mythbusters episode, but my recolection was that it was tailgate up vs. tailgate down, not cover vs. no cover. It was about how far down the air stream dropped behind the cab - the lower it dropped, the lower the milage, and with a cover it can't drop as far. Hence less "drag". But it's been a while, and my memory isn't what it was...

Col_Sanders · March 19, 2010

Crappy pics:

66nova · March 19, 2010

Mythbusters has actually tested this on two different occasions and actually got worse gas mileage with a cover. It has to do with a vortex of air that is created by the bed/tail gate that allows most of the air to glide over the top of the truck. They also found that driving with the tailgate down did not yield better mileage.

So a big +1 to what has been said above. Buy a cover for keeping cargo dry.

I have had a cover on both of my last two trucks and never got any better mileage.

I saw that Mythbusters episode, but my recollection was that it was tailgate up vs. tailgate down, not cover vs. no cover. It was about how far down the air stream dropped behind the cab - the lower it dropped, the lower the mileage, and with a cover it can't drop as far. Hence less "drag". But it's been a while, and my memory isn't what it was...

Your recollection is partially correct. I think the name of the episode was tailgate up vs. tailgate down. But your memory of the results are a little off. They have actually had two episodes about this. The initial episode and a fan requested revisit. They tested: tailgate up, tailgate down, bed cover, no tailgate, and a tailgate net. Tailgate up and the tailgate net actually got the best mileage. The bed cover was next and then the tailgate down and tailgate off.