Anyone here ever compared the highway mileage of their ST with a cap installed vs. just having the tonneau (or even no tonneau)? Considering a cap for extra space in the back, just want to know what to expect. Also, how hard are the caps to remove? Thanks
Cap vs. Tonneau MPG
- Thread starter P M
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george dunphy
Member
PRM,,, I put a topper on my 08 mainly for the extra space. I needed space for a dog grate and hunting decoys. Prior to putting a topper on I made a trip from Denver to Nova Scotia. The next summer I made another trip to Nova Scotia with the topper and noticed as much as a two per gallon increase in mileage. I figured it may have been the topper. I do enjoy the topper for the space, my buddy and I can load up the ST for our week long trips to South Dakota in the Fall for hunting trips. The added height is great when you start stacking things higher than the bed rails.
It has already been shown that there is no significant mileage difference for a Sport Trac with or without the tonneau cover.
MythBusters also did some extensive testing on several F150's regarding the myth that you get better gas mileage if you put the tailgate down. It was found that with the tailgate up, the air entering the bed swirls and builds a bubble of air in the bed that forces the air going over the cab to continue on past the truck bed making the truck more aerodynamic and improving gas mileage. Even those "Net" style tailgates did not improve mileage, so it leaving the tailgate up was the winner.
I would think that the cap over the bed would act like the bubble of air formed by the tailgate being up, and the mileage would be similar.
Remember that added weight can decrease mileage, especially in stop and go city driving, but if it's not too heavy you probably will not notice much difference.
In the end it does not appear that covering the bed of a late model truck has much impact on mileage. It appears that a cap or tonneau cover only serves to protect cargo from the weather.
...Rich
MythBusters also did some extensive testing on several F150's regarding the myth that you get better gas mileage if you put the tailgate down. It was found that with the tailgate up, the air entering the bed swirls and builds a bubble of air in the bed that forces the air going over the cab to continue on past the truck bed making the truck more aerodynamic and improving gas mileage. Even those "Net" style tailgates did not improve mileage, so it leaving the tailgate up was the winner.
I would think that the cap over the bed would act like the bubble of air formed by the tailgate being up, and the mileage would be similar.
Remember that added weight can decrease mileage, especially in stop and go city driving, but if it's not too heavy you probably will not notice much difference.
In the end it does not appear that covering the bed of a late model truck has much impact on mileage. It appears that a cap or tonneau cover only serves to protect cargo from the weather.
...Rich
EddieS'04
In Memoriam 1950-2022
MIT, performed the same test that Richard posted. Same conclusion, no mpg difference.
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This is the ST "S" model with optional tail cone. LOL
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EddieS'04
In Memoriam 1950-2022
Steve,,LOL!!!!!!!!
fftopic:
I havent thought about it before. But JBA uses that tail cone technology in their header collectors. Called the firecone. I wonder if they got the idea from NASA.? It is about air flow.
:back2topic:
fftopic:I havent thought about it before. But JBA uses that tail cone technology in their header collectors. Called the firecone. I wonder if they got the idea from NASA.? It is about air flow.
:back2topic:
george dunphy
Member
PMR,,, I tried, Enjoy the space and hopefully extra mileage. I only reported what I figured with my ST...Regards,,,,,Press-on, IDM....................525
george dunphy
Member
george dunphy
Member
Well guys I figured, twelve thousand miles, in one year, would be a good test. Maybe I miss figured somewhere, yaa,. Enjoy your ST anyway.....525
Johnny O
Well-Known Member
I think a cap would be more aerodynamic but any potential gain would probably be offset by the extra weight.
My first truck was a '99 Ranger 4x4 with a 3.0/stick. Had to be one of the slowest vehicles ever foisted on America since the diesel Chevette. The tonneau never seemed to affect mpg BUT it would definitely hold speed better on the highway with the tonneau on.
My first truck was a '99 Ranger 4x4 with a 3.0/stick. Had to be one of the slowest vehicles ever foisted on America since the diesel Chevette. The tonneau never seemed to affect mpg BUT it would definitely hold speed better on the highway with the tonneau on.
David Ponder
Well-Known Member
I orignally had a Tonneau cover, and swapped it for a cap.
The cap is indeed heavier, and you do lose some visibility.
I also noticed about a 1-2 mpg decrease when I swapped them.
The cap is indeed heavier, and you do lose some visibility.
I also noticed about a 1-2 mpg decrease when I swapped them.
Larry Hampton
Active Member
I'm like 525, I put an Astro shell on mine (had a vinyl cover) and noticed better mileage on my truck. It's a 2wd with a towing package. I'm getting at least 400-425 miles per tank. Used to get around 375 prior to that.
1320stang,
I'm not questioning your mileage increase, however when people state mileage based on miles per tank of gas, I really don't accept that as an accurate method of checking gas mileage. That's just an estimate, and highly inaccurate.
...Rich
I'm not questioning your mileage increase, however when people state mileage based on miles per tank of gas, I really don't accept that as an accurate method of checking gas mileage. That's just an estimate, and highly inaccurate.
...Rich
EddieS'04
In Memoriam 1950-2022
RL,,that is very true. My '88 T-Bird onboard digital did it this way. It was very inacurate. Found it to be 5 mpg +or- off all the time.
As a retired Instrument Tech. I think the accurate way, would be to have a flow meter on the fuel line.
Some of our members that have a gen 2 trac have proclaimed theirs to be accurate. So I wonder if Ford is using a flow meter? Electronicaly, I have seen some miniture meters, before I retired.
Eddie,
I agree. I always recommend the old fashioned way of testing gas mileage....Fill up the tank, drive for at least 100 miles in normal traffic, Refill the tank back at the same pump you filled up at and then use the old math formula of dividing the miles driven by the gas used and include all the tenths or hundreds of a gallon that the pump shows and all the tentsh shown on the odometer.
I lot of people just round off the puimp to the nearest gallon, or the odometer to the nearest mile. That is inaccurate as well. Of course the more miles you drive the less significant are the minor errors. That's why I don't think a Tankfull of gas is an accurate way to calculate MPG.
...Rich
I agree. I always recommend the old fashioned way of testing gas mileage....Fill up the tank, drive for at least 100 miles in normal traffic, Refill the tank back at the same pump you filled up at and then use the old math formula of dividing the miles driven by the gas used and include all the tenths or hundreds of a gallon that the pump shows and all the tentsh shown on the odometer.
I lot of people just round off the puimp to the nearest gallon, or the odometer to the nearest mile. That is inaccurate as well. Of course the more miles you drive the less significant are the minor errors. That's why I don't think a Tankfull of gas is an accurate way to calculate MPG.
...Rich
Phill R
Active Member
I check my MPG periodically.
Last fall, I put a cap on in place of the factory hard toneau cover.
After a couple of tankfulls, I have found no real change in MPG.
I have figured out that I have tripled the amount of useable volume inside.
With the cap, I am able to load the same amount of camping gear that would fit in a full size pickup bed with just a cover!
Last fall, I put a cap on in place of the factory hard toneau cover.
After a couple of tankfulls, I have found no real change in MPG.
I have figured out that I have tripled the amount of useable volume inside.
With the cap, I am able to load the same amount of camping gear that would fit in a full size pickup bed with just a cover!
I'm putting in the order this week so I should have it about three weeks. I track every tank (miles driven/gas to refill tank) so I'll know what it does to the mileage. FYI, I've found the computer computed MPG to be very accurate on the 08 ST. It computes some form of running average, so it will lag a bit if you change driving conditions (i.e. all highway to all city or vice versa), but it matches calculations over any reasonable length of period.
There was never a towing package on the 1st gen ST's. Just a heads up...
Tom
Thomas Rogers
Well-Known Member
If really concerned with gas mileage the ST isn't the right vehicle to begin with. No big mpg difference should be noticed due to the cap.
TJR
TJR
