Tonneau Cover+MPG

I ‘ton-know what y’all yammering so much about gas...perhaps yah should git to a doc or sumthin.

 

Shaddup an get bak to drinkin shin.

 

Here's one. There are many. My point is yes, it can save depending on weight but only tenths or hundredths. They can even decrease mpg!
Sometimes engineers do not work in reality.
https://www.torquenews.com/4140/does-bed-cover-really-increase-your-toyota-tundras-mpgs

 

Unlikely. If so, Toyota would have put them on all their trucks stock and raised their EPA figs by 2mpg across the board.

You’d be lucky to get 2mpg more with a purpose-built aero shell.

 

Mine made no noticeable difference.
8k miles. Roughly 50/50 without/with the cover.
For the record, it's a soft cover, so weighs nothing, but does flap slightly.

 

For the love of all that is Holy, this fucking place....

Read this:

https://www.consumerreports.org/cro/news/2013/08/pickup-truck-tailgates-and-fuel-economy/index.htm

"With the tailgate up and no tonneau, we got 22.3 mpg. Dropping the tailgate decreased efficiency to 21.5 mpg. That 4-percent difference means that driving the Ram all year exclusively on the highway could cost the owner an extra 20 gallons of gasoline."

"We found that covering the bed with a soft tonneau cover was even more detrimental, dropping fuel economy to 21.4 mpg."

Real study:

http://csus-dspace.calstate.edu/bitstream/handle/10211.9/169/combined-finished.pdf

Conclusion:

Drag coefficient baseline: 0.3453
Drag coefficient with tonneau: 0.3413

Minuscule drag coefficient. 1.16%. Slightly less lift coefficient - 6.64%.

Go to page 48 for the tonneau cover portion.

For reference, the study noted that a 3d aero cap provided the best aerodynamic improvement - drag reduction of over 19% and lift reduction of almost 41%.

Those numbers are way higher than the tonneau and they netted a field economy increase of...drum roll.......

0.003 gallons per mile, or whopping 1.055 mpg!

If you use the equation provided in the study, the tonneau nets you a fuel increase of:

0.1759 MPG!

 

That's YUGE mileage! I'm seeing 21 max. I've got one size up tires, 36/32 psi, bak flip tonneau cover, rest is stock. What psi and tires you running?

 

Curious only, did you compensate for the new tire diameter in your calculations?

 

My truck is completely stock, no mods at all.

 

Exactly. Gate up, no cover is the most efficient. Less air is hitting surfaces of the truck. It is getting rolled over the tail gate by a big ball of air behind the cab.

 

I did.... conversion chart did the math for me. I went 265/70/16 to 265/75/16 with duratracs, E rated.

 

so your saying you get 45mpgs?

 

With as much a difference as driver input can make, it's pretty hard to make definitive statement from a sample size of 1.

If you really want to test it you need to standardize a drive cycle, test it with it on, then off, then on, then off a few times to remove the other variables then analyze the results and tease a conclusion from the data.

If you really want a bed cover to increase mileage, a shaped aerodynamic bedcover would be the way to go. Emulate the shape of the back half of a prius. (Or any modern sedan really, they all go for that round shape to reduce the size of the wake. Or go for a full boat tail.

 

I really want to see someone do the boat tail on a third gen. But classy.

 

So it looks like if you drive around with only a qtr tank of gas all the time and loose 10lbs of body weight you get better gas mileage improvements than all these factors combined. Of course having to fill up with a qtr tank frequently will mean more King Size Snickers bars a Cubmy's so the 10lbs of body weight increase might more than offset it...however since this will decrease you life expectancy comparatively, so my strategy will be to monitor the gas gauge and go to the station when it needs fuel.

 

The only thing they improved mpg is the OVTune.

 

As I have mentioned in other posts, my daily commute is just over 160 miles. I have done the trip numerous times (4 days a week) with my cover and without. On most days I'm setting the cruise control and just going, and the drive is like 80% freeway. The difference I have noticed is... none. With or without the cover, my commute to work is right at 28, my commute home from work is right at 19 (house is 3000 feet higher elevation than work). I'm going to say that the cover does little or nothing for gas mileage. If I were buying the truck again, I would not have the cover from factory and instead get one of those bed toolboxes. That is on my list of things to change in the nearish future. The bed is more usable when open to me but I like the better protected storage the cover allows.

 

Fair enough. It makes intuitive sense that it would reduce drag due to the turbulence caused truck bed.

I wonder if a light-weight camper would increase MPG

 

If it were the right shape, a curve flowing down from the top of the cab to the tailgate. To see a benefit you'd have to spend enough time cruising at a speed where drag is a significant portion of the fuel used. If you do a lot of stop and go at lower speeds you won't get the advantage of the topper, but would have to accelerate it's weight, then convert that energy to heat when stopping again.