Tonneau and fuel mileage

Thinking about adding a tonneau cover, not for mileage purposes but that would be a nice bonus.

Do tonneaus have much of a positive impact on mileage on these trucks? I feel like long ago I read that it's possible for them to have a negative effect rather than a positive one.

 

No negative impact and not any real change having one as far as MPG.

They are nice on a crewmax if you use the rear window, without one dust, dirt and crap swirls up from the bed, thru the back window and into the cab.

Ive had trucks with and without, certainly prefer having one.

 

Best for keeping your items out of view of others and (mostly) out of the elements.

I've always been told they hinder fuel mileage because of how the air circulates in the bed. If there's a difference, it's so small it's not noticeable. I've never seen any difference in my vehicles.

 

Yeah, I had read years ago that you'd get better mileage with the open bed because of the vortex of air that develops in the bed and behind the cab. But I've also seen people argue the other way; and on another forum last night saw someone say their tonneau increased their highway mileage by 3 MPG. I would believe there could be an improvement, 3 seemed overly optimistic.

 

That's a good point about the rear window. I do like using that rear window, but as it is I can only use it when the bed is clean.

 

I suspect any minimal gains on the aero side would be eliminated by the extra weight that you are carrying, making it essentially a wash. My Tundra had one from day one, so I can't state if there was a difference, but on my Tacoma, I added one midway through and there was no noticeable change for better or worse.

 

A tonneau cover will help your mileage but under certain conditions. Gotta remember that aerodynamically, drag from the bed/behind the cab is only a piece of the whole picture. Ride height, rake, and of course a huge flat grille all have an effect too.

At speeds 65 or under you'll see the tonneau cover making it's greatest effect. These trucks rapidly lose mileage over this speed because the front end is so blunt and large, and the factory ride height is higher than most others. If you drive faster you probably won't see a difference because the tonneau cover doesn't help much compared to how much the truck's front end holds you back.

I can maintain 23 mpg in my 2018 with a huge hi rise topper at 40mph, in flat ground and 5th gear. At 75, I'm lucky to get 16-17. I get worse mileage with the topper than an empty bed. Best was with a mattress in the bed, flush with the rails and tailgate. 20mpg comfortably at 65mph from PA to FL. I'd have gotten maybe 19 without the mattress, but it was in a mattress bag that flapped a little bit.

 

Tonneau cover may help, but mostly I got mine to keep bed dry/covered, and I use the rear window all the time so it keeps crap from flying in. What I can tell you is windows up and AC on at highway speeds is 2-5 mpg better than no ac and all windows down, so guessing the Tonneau will help too.

 

I got a roll up cover as well and never really thought about better gas mileage. Tbh, I don’t think about anything gas mileage on our trucks. In the end it’s a losing battle.

 

Guess I'll find out eventually here. I ordered a TruXedo Deuce. Supposed to be here Friday.

 

Windows will create drag at highway speeds which will affect mpg's.

 

I was making a point, but...um...thanks?

 

Sorry man. Read it the wrong way. It was 7:30am when I commented that and clearly my coffee hadn’t kicked in yet lol yeah your point is valid!