Truck camper shell / cap?

JerryG · Jul 19, 2007

I have a fiberglass camper shell cap on my F150. It was on the truck when I bought it, so I don't know what effect it has on mileage. It is level with the top of the cab and it has the sealed pass though to the cab. What I want to know is how does it effect gas mileage? Will the mileage be better if I take it off or will my mileage drop?

RoyJackson · Jul 19, 2007

Better aerodynamics with it on. That bed really increases drag at speed.
Of course, the weight of the cap increases fuel use, so it is a bit of a balancing act. If you only use this truck at lower speeds, it would pay to pull it off.

If you do pull it off, drop the tailgate when running at speed (if it's safe), or get one of those mesh tailgate replacements.

crbr · Jul 19, 2007

RoyJ has valid points, no doubt.

IMHO....drag and fuel? Not worth the worry to me. If one can detect any better or worse mileage within + / - 1 MPG... well, good luck. Point is, a topper will not make a hill of beans difference.
After a certain point of expenditure, it's like a Jaguar or a fancy Mercedes... if you have to ask how much it cost, you can't afford it.

I could not do without my topper. I have had one on a number of trucks since 1980, Just bought a 2007 GMC this past week. That was the first thing back on it.

Enjoy the topper if that's your preference. If not, it has a decent market value when you find someone looking. Brand new, these toppers now are upwards of US$1500 - $US3000 for a basic topper, OEM code match painted, frameless windows, fold-down front cab window, interior light, and interior carpet (to avoid fiberglass shreds).

jwstewar · Jul 19, 2007

RoyJackson said:
Better aerodynamics with it on. That bed really increases drag at speed.
Of course, the weight of the cap increases fuel use, so it is a bit of a balancing act. If you only use this truck at lower speeds, it would pay to pull it off.

If you do pull it off, drop the tailgate when running at speed (if it's safe), or get one of those mesh tailgate replacements.

Here is a link that says you should drive with tailgate up: Car Talk I've also seen a couple of episodes of Mythbusters, both of them have said leave the tailgate up. I believe there was also a discussion here on TBN a few years ago about driving with the tailgate up or down. There was a link in it about someone doing a college thesis on it and it also proved you should run with the tailgate up.

Bird · Jul 19, 2007

Topper or cap on or off; I'll bet you cannot tell a difference in the fuel mileage either way. And, yes, it was long thought that opening the tailgate would help gas mileage, but every actual test I've read reached the opposite conclusion, although again, the difference is so slight that I'll bet most people would never be able to tell there was any effect either way.

RoyJackson · Jul 19, 2007

Wow, I've been living an old wive's tale?

Thanks, Guys! I stand corrected!

jwstewar, that link didn't take me to the article. But with your's and Bird's posts, I did a bit or research

jwstewar · Jul 20, 2007

Sorry Roy, I was trying to clean the link up and guess I got it a little to clean. Here is the article I was refering to: Car Talk

RoyJackson · Jul 20, 2007

jwstewar said:
Sorry Roy, I was trying to clean the link up and guess I got it a little to clean. Here is the article I was refering to: Car Talk

WOW!!
That was great! thank you very much!

jimg · Jul 20, 2007

I have a newer Chevy 1/2t w/ a gasoline motor which I bought w/o a cap and later added it. I have about a yrs worth of driving w/o and bit more w/ it on. I also did a large amt of hwy driving during the past 2 yrs. While I didnt keep perfect records I found theres almost no diff between having it on and not. According to the installer my shell weights about 200# or so.