Adding a cap is supposed to IMPROVE your gas mileage right?
Seems like my gas mileage is getting worse since getting a cap, I don't get it.

Habibi

 

I don't think a cap improves gas mileage. A fiberglass cap weighs a couple of hundred pounds doesn't it? Plus it sticks up and catches any side wind.

(I'm still trying to figure where the gas savings is)

 

Me too,

Since my cap is streamlined to the shape of the truck, I was thinking that there would be less drag and resistance ... resulting in improved MPG. I wasn't expecting much, but it seems it's gotten a tiny bit worse.

Maybe you're right, and the extra 200 pounds canceled out any drag reduction.

Thanks
Habibi

** Whatcha doing up so late? I thought only us online poker players were the only night owls.

 

This is only my theory, so here it goes. With a cap, you've raised the surface area behind the truck and when the air flows over it, it gets "sucked" down towards the ground and that creates a vacuum right behind the cap and the tailgate. This additional vacuum will cause more drag on the rear of the truck. I wouldn't have thought it would be enough to actually calculate, but there you go.

Good luck.

 

I believe the additional weight is the problem. Thats easily 250-300lbs. I think somewhere i read, that adding/subtracting weight is 100lbs=5hp. So you now have to push the go peddle that much more, so you aren't saving anything, and you're lucky if your mog stays the same

 

Here, this link will tell you guys everything you want to know, and probably more than you bargained for...

http://mars.acnet.wnec.edu/~ehaffner/did.htm

I guess Dodge trucks are useful for something.

 

ljmanscrew,

Thanks for that, it was really interesting.
I had no idea.

Habibi