Tonneau Covers VS MPG Performance

[Scap]

Funny I was going to say the same thing. Calculus sucks, I know very few people who enjoy doing it longhand. I have calculators, and I've made Exel templates that allow me to simply plug in the numbers for various formulas. You have to know how to do it so you can validate your results and/or identify something that doesn't seem right, but we're not doing it any more than we need to either.

I did the same thing yesterday. Built a spreadsheet to calculate building area, perimeter, and surface area. All I input is the length, width, eave height, and pitch. Excel does the rest. No more fat finger errors halfway through.

 

[Redfour5]

There are actually two Mythbusters tests for this one. The first (which I remember better than the second) seemed to point out no tonneau cover is better than the other options, but they revisited the testing (second episode) which (if I remember the episode correctly) pointed to tonneau covers being better for MPG than no cover or a canopy.

I'm interested in this as well, so I'll follow this thread.

They said lighters can't blow up on their own too. I had a cheapo clear one in the sun and it blew up, scared the poo out of me, sharp little pieces of plastic everywhere. I think the little structural pieces inside acted like a lense...

 

[JOnline76]

I'll add my info to this thread in case it is intereting:

I've just removed by Rambar and replaced it with a Truxedo Sentry (as I could not get them both to fit). I did not weigh them both but can certainly tell from lifting them both that the Rambar is slightly heavier than the tonneau cover, so that should be a net reduction in weight. Also, with the Rambar removed the air flow will likely be slightly improved.

I don't know when the truck engine is supposed to "break in" to get better gas mileage. I've seen posts that suggest thousands of miles before that so.. all I can do is go by the average MPG I've be calculating. (method: by comparing mileage from the odometer at every fill-up and calculating it out manually during fill-up with what the manual calls for, 89 octane at Shell stations exclusively).

I've calculated it 4 times so far with a combination of city and highway and I drive between 70 and 80 mph on the highway, and I do not drive aggressively in the city, instead I do try to keep my foot off the gas - so a mix of good/bad habits essentially. I leave MDS doing it's thing and leave the start/stop enabled and try to maximize it by not inching up at lights.

2022 RAM 1500 Rebel - 5.7L Hemi with eTorque (off road package incl. aggressive tires, skid plates etc) - currently: 1,491 miles on odometer

Mileage: 601 (maximized MPG with driving style and speed)	15.70 MPG
Mileage: 782 (drove reasonably normal)	13.83 MPG
Mileage: 1,015 (drove reasonably normal)	14.42 MPG
Mileage: 1,257 (drove reasonably normal)	13.02 MPG

To state the obvious I'm not thrilled with the discrepancy between actual MPG and the EPA sticker. They really should break out the off-road trimmed trucks differently so you can see what you're more likely to get. I suspected I would not be getting 22 MPG, but at this MPG, I should have just gotten the TRX

I just switched it out today at less than 1/2 a tank, so I will fill up again and not really count the 5th measurement I take, but from then on, any new calculations (6th and beyond) should be interesting in terms of any increase or not.

I'll update the thread with calculation 5 & 6.

Cheers!

 

[HSKR R/T]

Modern trucks are designed in the wind tunnel for aero. This includes airflow over the bed. Back in the 80s and earlierz tonneaus probably helped a lot with gas mileage. Modern truck, get a tonneau for looks and securing things in the bed and don't even consider fuel mileage

 

[vincentw56]

They said lighters can't blow up on their own too. I had a cheapo clear one in the sun and it blew up, scared the poo out of me, sharp little pieces of plastic everywhere. I think the little structural pieces inside acted like a lense...

But it didn't blow up on its own, it had help from the sun.

 

[NavyChief]

You guys and your tailgates/spreadsheets/engineering, everybody knows you install these to get amazing fuel mileage, engine performance and cure erectile dysfunction. It says 10-30% increase and you know internet numbers don’t lie.

“【FUNCTION】By magnetizing oil molecules, the combustion is more complete, and the effect of fuel saving and acceleration is achieved”

How do you argue with that?

Amazon.com: Modengzhe Magnetic Car Fuel Saver, Clip-on Type Magnet Gasoline Saver for Automobiles : Automotive

Buy Modengzhe Magnetic Car Fuel Saver, Clip-on Type Magnet Gasoline Saver for Automobiles: Automotive - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[JOnline76]

Just to be clear - I didn't install the tonneau cover to specifically improve gas mileage, I wanted the ability to cover items in the truck bed and keep the weather out on road trips so we can use the back seats for - well - seats. - I'm just curious how specifically removal of the rambar and replacement with the tonneau cover will affect MPG as the rambar upsets the "normal" profile of the truck that the EPA MPG is based upon, and then there's the small difference in weight. If nothing else, it will be an interesting practical experiment since I was already tracking MPG pretty consistently. - And you're right I did NOT buy this truck for MPG.

 

[asgadf/lkjnadsfg]

You'd want a test to compare the drag co-efficient of the truck with and without the tonneau cover.

A quick search found the test in the link below, and you could surely find more. The bottom line on the test in the link below says that the tonneau covers they tested changed the drag co-efficient in a manner that indicates it "could" improve fuel economy by 1.8%. Note that they used the word "could". They didn't say it "did" or "will". They said it "could". I don't know anything about the group that did this test, but that type of test is what I'd be looking for if I were trying to find an answer to the question.

https://www.agricover.com/downloads/pdf/2007_windtunnel.pdf

That is a far, far cry from 15%. A manufacturer is in the business of sales, and they will tell you whatever they need to tell you to sell the product.

 

[JOnline76]

You'd want a test to compare the drag co-efficient of the truck with and without the tonneau cover.

A quick search found the test in the link below, and you could surely find more. The bottom line on the test in the link below says that the tonneau covers they tested changed the drag co-efficient in a manner that indicates it "could" improve fuel economy by 1.8%. Note that they used the word "could". They didn't say it "did" or "will". They said it "could". I don't know anything about the group that did this test, but that type of test is what I'd be looking for if I were trying to find an answer to the question.

https://www.agricover.com/downloads/pdf/2007_windtunnel.pdf

That is a far, far cry from 15%. A manufacturer is in the business of sales, and they will tell you whatever they need to tell you to sell the product.

I guess all they really need to do is find one truck - no matter how old - that demonstrated 15% increase in their testing. right?

 

[asgadf/lkjnadsfg]

I guess all they really need to do is find one truck - no matter how old - that demonstrated 15% increase in their testing. right?

The great thing about being the person selling the "15% improvement" pitch is they don't have to prove anything. They just make the claim and hope it sells more stuff.

Unless you're in a highly regulated industry (like prescription drugs, the securities/investments industry, etc) you can generally get away with all kinds of wild claims in your marketing.

Not a lot of people know it, but I got a 2%-3% increase in fuel mileage after I signed up for this site.

 

[Rick J]

Mythbusters study MPG savings of various bed modifications

www.dakota-durango.com

Do tonneau covers save gas? - Peragon®

It’s all about drag. Generally, anything that reduces the drag on a vehicle while it’s going down the road will improve its fuel efficiency. Does a bed cover improve gas mileage? It does if it reduces drag.

www.peragon.com

From the Mythbusters:

Tailgate Up or Down Revisited: Mesh tailgate, hardcover, tailgate removal​

See: Tailgate Up or Down

For the original myth they did a driving test and a water vortex test, both of which showed that you save more gas with the tailgate up. Their viewers suggested that they test three new conditions:

• Hardroof cover over pickup bed
• Mesh tailgate
• Remove the entire tailgate

They had a much simpler test setup this time. They had an electronic flowmeter hooked into fuel line of Jamie's pickup. Adam: "For anyone out there that wants to e-mail telling me that we screwed up this test, we have already calibrated this thing, to this car. So it's going to be perfect!" They drove the pickup truck up and down the stretch of 101 around Candlestick and the Cow Palace.

• Tailgate down: 5.2 gallons/hr @ 55mph. 1.2 gallons/hr @ 25.
• Tailgate up: 5.0 gallons/hr @ 55mph. No reading for 25mph given, but tailgate up was once again confirmed as more efficient.
• Hardcover over pickup bed: 5.0 gallons/hr @ 55mph. 1.2 gallons/hr @25mph
• Tailgate mesh: 5% more efficient
• Tailgate removed: about the same as tailgate up and hardcover

Mesh was most efficient by 5%

A little off topic here but I've got to say there was something wrong with Jamie's Dakota. They claim 20 mpg at 25 mph and 11 mpg at 55 mph. My 2000 Dakota with the 5.9 V8 got around 16 mpg (with a soft tonneau cover) at 60 mph. Not sure what it got at 25 because I never drove at 25 long enough to measure it.

 

[HSKR R/T]

A little off topic here but I've got to say there was something wrong with Jamie's Dakota. They claim 20 mpg at 25 mph and 11 mpg at 55 mph. My 2000 Dakota with the 5.9 V8 got around 16 mpg (with a soft tonneau cover) at 60 mph. Not sure what it got at 25 because I never drove at 25 long enough to measure it.

I agree, my 0 Dakota R/T, even stock averaged 14-16 mpg daily driving. I got a best of 18mpg cruising at 75mph in AZ one time. Now that it's modified, I average 17mpg on the highway and have gotten a best of 19mpg drafting a buddy pulling an enclosed car trailer at 70-75mph.

 

[OCD Solutions]

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.

My experience exactly. I've run both snug-top Aero canopies and bed covers and found no significant improvement in mileage with or without.
Although I will say that mileage is always better without a bed full of wet. heavy snow or ice.