Tonneau Covers VS MPG Performance

[RebelWraith]

If I'm reading that ticker correctly in the background the test is being done at 20.2 mph (32.5 kph). I wonder how much, if at all, the flow changes at highway speed.

 

[Shots]

Nice! Thanks for sharing that.

 

[Biggiehorn]

I've done "testing" with covers and without. By testing I mean I've calculated/logged mileage on my Ram before buying covers and continued after installing them. This "testing" has been on multiple Rams with various cab and bed configurations with various engines (4.7L and 5.7L). It may also be worth noting that I am an engineer (Mechanical, not Automotive so take it for what it's worth).
I've had pretty much every iteration of tonneau cover over the years, including vinyl, aluminum roll top, solid hinge, tri-fold (aluminum and composite) and different design/manufacturer of most of them. I've had very little difference in fuel efficiency which was closer to 5% on the best, rather than the 15% they may claim.

Even if you could reach 15% though, how much do you have to drive to recoup the cost of a cover?

Calculating the lofty, and personally unmet, estimate of 15%.
Lets figure the average mpg of 18 for the 5.7L (15 city / 21 hwy per the window sticker).
If you drive 500 miles, you'll burn 27.77 gallons of gas.
A 15% increase from a tonneau results in 20.70 mpg. Over 500 miles you'll burn 24.15 gallons of gas.
You've saved 3.62 gallons over 500 miles.
At the current average mid-grade fuel cost of $3.14 per gallon, you'll save $11.36 for every 500 miles you drive.
With tonneau covers ranging from $200 for an affordable vinyl cover to $1100 for a solid fold like the Bakflip MX4 you've got a wide range of cost to recover.
The mileage required will be from 8,802 miles to 48,415 depending on the cost of the cover assuming you get the unverified 15% savings.

If you take my real world results of roughly 5% that distance to recoup the cost goes up because the savings goes down.
To do it all again for 5%:
If you drive 500 miles, you'll burn 27.77 gallons of gas.
A 5% increase from a tonneau results in 18.9 mpg. Over 500 miles you'll burn 26.45 gallons of gas.
You've saved 1.32 gallons over 500 miles.
At the current average mid-grade fuel cost of $3.14 per gallon, you'll save $4.14 for every 500 miles you drive.
The mileage required will be from 24,154 miles to 132,850 mile, using real world savings.

In short, buy the cover because you want a cover not to save money. It's no economically beneficial to buy it for the fuel savings. Even at the lofty estimate of 15% you would have to drive 2-4 years before you start seeing a savings (using 12K miles per year average).

[to calculate the distance required for a specific cover, divide the cost of the cover by the savings ($11.36 for 15% or $4.14 for 5%), then multiply that result by the 500 miles required to save that much fuel]

Truly appreciate the information and the time you invested to reply to the post. This was exactly the kind of information I was looking for when asking in regards to real world testing on the Rams. I assumed that there would realistically be little to no “true” benefit or disadvantage from an mpg standpoint. That’s why I find it so odd that pretty much everyone seems to list it as a major selling point. Great marketing tactic I suppose and I guess I can understand why when looking at the big picture. I asked mainly just to spark the conversation. I would never purchase a cover strictly on mpg claims, but it almost seems like it is one of the primary factors as to why so many truck owners do decide to buy one.

 

[Biggiehorn]

Wind tunnel testing of the fifth gen Ram. This shows why adding a tonneau cover will not help with fuel mileage and the added weight will actually hurt gas mileage fractionally.
View attachment 104173

Nice find! I hadn’t seen this previously, but this was also one of my initial thoughts. Speaking from the aerodynamic standpoint of most trucks these days, this appears to be somewhat of the norm. I wondered how much wind was actually being pushed down into the bed, and how much difference the cover would actually make in a real world scenario.

 

[vincentw56]

Mythbusters video

 

[GKIII]

I installed a cover for security and weather protection of whatever I may be carrying back there. Whatever minimal aero gains achieved by said cover are likely entirely counteracted by the additional weight.

 

[Shawn19]

I currently have a soft tri-fold. On sometimes off sometimes, I notice my best numbers when it’s off. I see movement when it’s on, and I would guess it causes a bit of drag.

 

[Biggiehorn]

I installed a cover for security and weather protection of whatever I may be carrying back there. Whatever minimal aero gains achieved by said cover are likely entirely counteracted by the additional weight.

Agree completely. That’s honestly one of the only legitimate reasons for wanting one in the first place in my mind.

 

[Biggiehorn]

I currently have a soft tri-fold. On sometimes off sometimes, I notice my best numbers when it’s off. I see movement when it’s on, and I would guess it causes a bit of drag.

I’ve heard this claim as well. I’m sure it’s a much lighter option, but if it does create additional drag, you probably won’t see any benefit. What’s funny is a lot of the soft cover advertisements seem to be the ones that claim the biggest fuel economy improvements lol.

 

[MurphBigHorn]

I currently have a soft tri-fold. On sometimes off sometimes, I notice my best numbers when it’s off. I see movement when it’s on, and I would guess it causes a bit of drag.

I see mine ripple to as I drive.

 

[MurphBigHorn]

Anyone ever notice cab noise increase when adding side steps/ running board. My sidesteps are the only thing that really bothered me at first. Created a wind/ whooshing sound.

 

[CanRebel]

I just put a cover on my new Rebel. I never even thought about gas mileage or weight.
It cost $1200 (Canadian) from Dealer, Tri-fold Hard Mopar Black. Installed it myself.
I wanted it for look, and so crap doesn't blow in bed, or birds pooping on bed, etc...

I also already loaded if up with crap to put in garbage at work, didn't have tie it down

 

[vincentw56]

Anyone ever notice cab noise increase when adding side steps/ running board. My sidesteps are the only thing that really bothered me at first. Created a wind/ whooshing sound.

I don't have any noise from my side steps.

 

[Trooper4]

For those wondering about the mash tailgate replacement getting better mileage, it is most likely because it gets rid of most of the low pressure area behind the solid tailgate, yet still generates some of the air cushion in the bed that helps the air flow over the bed. With a low pressure area behind the solid tailgate, it generates drag via low pressure the same as low pressure generated by a wing keeps an airplane in the air. All about pressure differential. High pressure, push and low pressure, suck, ie, tailgates suck.

 

[Shots]

Truly appreciate the information and the time you invested to reply to the post. This was exactly the kind of information I was looking for when asking in regards to real world testing on the Rams. I assumed that there would realistically be little to no “true” benefit or disadvantage from an mpg standpoint. That’s why I find it so odd that pretty much everyone seems to list it as a major selling point. Great marketing tactic I suppose and I guess I can understand why when looking at the big picture. I asked mainly just to spark the conversation. I would never purchase a cover strictly on mpg claims, but it almost seems like it is one of the primary factors as to why so many truck owners do decide to buy one.

Glad to help, and I think it's a great conversation piece, you did well. I know a lot of people do buy them to save fuel, and they are often marketed that way. In many cases you do save a little fuel so the logic and/or marketing isn't flawed. The cost of the cover compared to the fuel savings is what often gets overlooked. Basically it may take a lot longer to come out ahead than people realize.

I installed a cover for security and weather protection of whatever I may be carrying back there.

That's the same reason I've had so many of them. Admittedly I was hoping to save gas with the first one back in the 90's, but I buy covers to protect and/or secure my cargo. Any fuel savings is a bonus.

 

[arod412]

Well for me, the tonneau cover is just for security of my stuff. Now that my new truck is on order ( when ever it arrives) it will have the rambox. This will be my first time with a rambox, so even though it comes with a bed cover (part of my package) I just might roll without a tail cover.

The other factors here is that if the person has a leveling kit or any kind of lift. That can also affect those real world numbers. The stock rake helps with getting those epa numbers listed.


2022 Big Horn Back Country
6/14…order placed
6/24…D status and Vin

2016 Dodge Charger scat pack and my wife 2021 Jeep Wrangler Unlimited Sahara

 

[834k3r]

I have no change in MPG with before and after the cover.

Now after installing my fx muffler I noticed a little decrease. It’s ether because I’m harder on the throttle or Because I started todo the mds lockout.

The study posted by @JBowman above says that the advantage at "normal" speeds is only about 1-2%--so I doubt any of us would notice an MPG gain after installing a cover.

 

[834k3r]

I've done "testing" with covers and without. By testing I mean I've calculated/logged mileage on my Ram before buying covers and continued after installing them. This "testing" has been on multiple Rams with various cab and bed configurations with various engines (4.7L and 5.7L). It may also be worth noting that I am an engineer (Mechanical, not Automotive so take it for what it's worth).
I've had pretty much every iteration of tonneau cover over the years, including vinyl, aluminum roll top, solid hinge, tri-fold (aluminum and composite) and different design/manufacturer of most of them. I've had very little difference in fuel efficiency which was closer to 5% on the best, rather than the 15% they may claim.

Even if you could reach 15% though, how much do you have to drive to recoup the cost of a cover?

Calculating the lofty, and personally unmet, estimate of 15%.
Lets figure the average mpg of 18 for the 5.7L (15 city / 21 hwy per the window sticker).
If you drive 500 miles, you'll burn 27.77 gallons of gas.
A 15% increase from a tonneau results in 20.70 mpg. Over 500 miles you'll burn 24.15 gallons of gas.
You've saved 3.62 gallons over 500 miles.
At the current average mid-grade fuel cost of $3.14 per gallon, you'll save $11.36 for every 500 miles you drive.
With tonneau covers ranging from $200 for an affordable vinyl cover to $1100 for a solid fold like the Bakflip MX4 you've got a wide range of cost to recover.
The mileage required will be from 8,802 miles to 48,415 depending on the cost of the cover assuming you get the unverified 15% savings.

If you take my real world results of roughly 5% that distance to recoup the cost goes up because the savings goes down.
To do it all again for 5%:
If you drive 500 miles, you'll burn 27.77 gallons of gas.
A 5% increase from a tonneau results in 18.9 mpg. Over 500 miles you'll burn 26.45 gallons of gas.
You've saved 1.32 gallons over 500 miles.
At the current average mid-grade fuel cost of $3.14 per gallon, you'll save $4.14 for every 500 miles you drive.
The mileage required will be from 24,154 miles to 132,850 mile, using real world savings.

In short, buy the cover because you want a cover not to save money. It's no economically beneficial to buy it for the fuel savings. Even at the lofty estimate of 15% you would have to drive 2-4 years before you start seeing a savings (using 12K miles per year average).

[to calculate the distance required for a specific cover, divide the cost of the cover by the savings ($11.36 for 15% or $4.14 for 5%), then multiply that result by the 500 miles required to save that much fuel]

I would add if any of us are trying to maximize fuel economy, we should've gotten in line to buy a Tesla.

 

[834k3r]

Anyone ever notice cab noise increase when adding side steps/ running board. My sidesteps are the only thing that really bothered me at first. Created a wind/ whooshing sound.

I installed my running boards a couple weekends ago and haven't noticed increased wind noise.

 

[Biggiehorn]

I would add if any of us are trying to maximize fuel economy, we should've gotten in line to buy a Tesla.

My buddy went to get a model 3 and immediately changed his mind when he got the insurance quotes. What money you save in fuel, you'll spend on the additional insurance premiums. That's the case down here in FL at least. His insurance rates for the year were going to triple from the price he was paying to insure his Mazda3. Different topic for a different day, but I was in shock when he told me the best insurance quote he could find was just over $3k a year lol.