[Turbio!]

Pretty much what the topic states: does a truck cap (or camper shell) improve fuel economy and aerodynamics at all over an open, uncovered bed? What about a tonneau cover?

 

[Live-Wire]

They're more just for lockable/weathproof storage according to people who use them. Tonneau covers are similar.

If they improve or reduce fuel economy (it would depend on the design of the vehicle overall) it would be negligible at best. I would even think the hard covers reduce economy just due to the extra weight.... camper shells definitely would not improve anything if you're talking about what I think you are (those drop in 2-person accommodations) as they weigh quite a bit.

Probably 1/2 the truck owners I know have either a cover or a shell, not a single one of them mentions that their truck got better mileage. The other 1/2 are open bed and none of them have mentioned thinking about a cap/cover to improve mileage. They are purely stylistic, personal taste, or necessary (carrying loads that need to be weather protected)... The only thing I've heard is opening the bed is suppose to improve mileage - but myth busters says it makes it worse. Tho if you talk to enough pickup owners some say yes, some say no... so again, I think it comes down to the design of the truck again too.

 

[ChillOutPossum]

No, it does not. The added weight also helps lower your mileage.

I checked this out on my truck. Here's what I got:

Highway mileage (10 mile average) at constant 60 mph no hills WITHOUT Leer cap: 24.41 MPG

Highway mileage (10 mile average) at constant 60 mph no hills WITH Leer cap: 21.50 MPG.

 

[Sledge]

If you got more than a 0.5% improvement with a cap or tonneau cover, I'd be surprised. I'm betting no appreciable change.

 

[patrickvr6]

From what I can find any improvement is negligible (like .5mpg) and really depends on the shape of the shell. You will also be adding a couple hundred pounds which never helps.

What are you scheming now?

 

[cryption]

I got a taneau (sp?) cover for my Frontier and saw a 3mpg increase with highway mileage. I don't care what the mythbusters say.

This wasn't a camper shell, however.

 

[Turbio!]

Yeah, this is what I suspected. Weight would really only affect city fuel economy, because aero and gearing matters most for highway, but it seems whatever aero advantage is conferred is pretty meaningless.

Thanks for the answers.

 

[ChillOutPossum]

I got a taneau (sp?) cover for my Frontier and saw a 3mpg increase with highway mileage. I don't care what the mythbusters say.

This wasn't a camper shell, however.

And I saw a ~4 MPG decrease :laugh:

I guess it all depends on the aerodynamics of your truck, and what shape/type of cap you have.

 

[Sledge]

http://ecomodder.com/forum/showthread.php/commercially-produced-aerodynamic-pickup-bed-cap-583.html

This might work

 

[Turbio!]

lolwat

 

[cryption]

Awesome picture ....

 

[soldierguy]

Whether or not they improve fuel economy depends on who you talk to and if they are trying to sell you something.

I saw an independent study several years ago, but can't find the link to it. Their results were basically that tailgate down with no cap is the worst, a fastback shell (think Prius hatchback) is the best, and conventional caps are somewhere in the middle, along with no cap at all.

Weight is a factor...these things generally add at least 200 pounds to the vehicle. Not a huge issue on the highway, but around town it will drop your mileage a bit.

I've had a few trucks, and have driven them all with and without a cap. Never noticed a difference in fuel economy on the highway. My current truck is the exception...I have a folding canvas cap (think Wrangler soft top), and that probably hurts mileage on the highway since the top of it is not smooth like fiberglass or sheet metal...there's a big bow "peak" in the middle of the top.

 

[cryption]

http://www.agricover.com/index.php/products/category/C9/

That is the cover I had and I swear by it. Soft roll up - and I really do feel like it improved my mileage

 

[ChillOutPossum]

http://www.agricover.com/index.php/products/category/C9/

That is the cover I had and I swear by it. Soft roll up - and I really do feel like it improved my mileage

Wait, it improved the mileage? Or you just "feel like" it did? :laugh:

 

[patrickvr6]

Yeah, this is what I suspected. Weight would really only affect city fuel economy, because aero and gearing matters most for highway, but it seems whatever aero advantage is conferred is pretty meaningless.

Thanks for the answers.

What if you cover the trailing edge in those Airtab things?

With a few dozen of those and some fender skirts you could have a hypermiling pickup!

 

[G0to60]

I know they aren't the definitive in scientific research but the Mythbusters tested a bunch of different truck bed/tail gate products including a bed cap.

I believe that they found the best product to increase mpg was the tail gate netting because it did two things. First it took a lot of weight off of the truck. Second it kept the air pressure "bubble" in the bed that helped to keep drag down. Essentially acting like a hatch back type air flow.

 

[Turbio!]

What if you cover the trailing edge in those Airtab things?

With a few dozen of those and some fender skirts you could have a hypermiling pickup!

I'd also be laughed at by small children while driving down the street.

 

[cryption]

Wait, it improved the mileage? Or you just "feel like" it did? :laugh:

I never kept an exact track but after putting it on I got about 25 - 30 more miles per tank

 

[adrew]

I haven't noticed a difference at

 

[a1veedubber]

And I saw a ~4 MPG decrease :laugh:

I guess it all depends on the aerodynamics of your truck, and what shape/type of cap you have.

He is talking about a tonneau cover, not a cap. In my experience a tonneau will increase your MPG, but only slightly.