bbmartin

As far as fuel economy, has anyone noted a difference between having a canopy on their truck or not? The way I see it, it could go two ways:

1. The weight of the canopy could bring down your MPGs
2. The improved aerodynamics of the truck with the canopy might off-set the increased weight and actually improve MPGs.

I'm mostly interested in freeway results as this is how most of my driving is done, and would have the most effect on aerodynamics.

Dodgezilla

Mine is a high topper which "Looks" aerodynamic but when it's on the truck I lose about .5 mpg.

.boB

A cap isn't really that aerodynamic. It creates a big square back end, which becomes a dead vacuum space and increases drag.

CD in NM

You need wings on the back of the cap to solve that problem, they did a great job for the suv industry. There is a noticable gain to mpg's when you control the air at the tail end.


CD

Dodgezilla

Maybe some Airtabs would work. The people that make them say they are awesome!!!!! LOL

Seriously though, I thought about getting a spoiler for the top of mine. I haven't done it yet because it seems that the big problem is the wind coming around the sides and then swirling around in the back causing a drag.

Howy

I've had toppers on both of my trucks and can't say I've noticed any difference in MPG before and after. (Mine were/are flush with the cab) However, I do notice an increase in MPG when there is a good tailwind blowing behind me. The back of the truck is about the size of a small barn and catches a lot of air!!

Have a good one.

jswar

And all those claims that tonneau covers give you an increase in mileage... BS!

Dodgezilla

I had tonneaus on my last couple trucks and never saw a difference either. Mileage was the same as with no cover and with the tailgate up....

Rednax

I find my close-fit bed topper is worth about .75 mpg in winds that are not unfavorable. At least it does not hurt is an accurate statement. I've never had a straight tailwind, and, while 3/4 crosswinds are the worst, the smooth transition from cab to topper means there is only one "drop" for the air to compensate for, at the very rear of the truck (versus a two-step from cab to bed and then at tailgate).

The best topper isn't manufactured at present: A wind-tunnel tested Aerolid (see threads by "Bondo" on Ecomodder; looking for financing) is worth double-digit percentages:



Some great DIY over there as other truck owners are doing mock-ups to see what works (in coroplast) before building the real thing for themselves.

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dott

Did anybody ever see the episode of Myth Busters where they did tests on different bed effects. The simple tailgate did the best. They tried no tailgate, vented tailgates, hard tonneau covers and some other stuff. The only thing better was a lightweight tailgate with very minimal venting. Has to do with the way the air flows over and around the cab into the bed. The tailgate actually creates a swirl in the bed and behind the cab that helps direct the air coming over the cab. Not intuitive but kinda interesting.

jballou

What about golf ball dimples all over? That was cool. Can someone try it for us?

pronstar

Dimples are beneficial for rotating spheres as they move through the air.