MPG Indicator vs Math
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New User
Joined: Oct 2017
Posts: 16
Likes: 0
From: Whatcom County, WA
MPG Indicator vs Math
I've been watching the miles per gallon indicator on the display and it doesn't seem to match the math when I fill up at the pump. I'm only on my third fill up, but the math always comes out about a half a mile per gallon less than what the indicator on the display reads.
Thoughts?
Thoughts?
Elder User
Joined: Sep 2016
Posts: 781
Likes: 6
From: Edmonton Alberta Canada
The fuel consumption of the engine is not linear and depends on may factors. I would not hold any of it as the truth above all else.
Driving conditions style wait times. I also recall they changed the system as it was over estimating mileage and causing issues.
I do believe there is posts on here about the massive fuel mileage debate.
Driving conditions style wait times. I also recall they changed the system as it was over estimating mileage and causing issues.
I do believe there is posts on here about the massive fuel mileage debate.
Posting Guru
Joined: Apr 2017
Posts: 1,655
Likes: 21
From: Western MA
I've been watching the miles per gallon indicator on the display and it doesn't seem to match the math when I fill up at the pump. I'm only on my third fill up, but the math always comes out about a half a mile per gallon less than what the indicator on the display reads.
Thoughts?
Thoughts?
If you are using larger diameter wheels its going to make your MPG indicator read low. Exactly how low would be based on your wheel size.
Fleet Mechanic
Joined: Aug 2017
Posts: 1,274
Likes: 26
From: St Louis Suburbs
I have found the computer on these Super Duty's is pretty accurate compared to other cars from Japan or Germany I have owned. Those VAG and Nissan manufactured vehicles could be off as much as 2.5 MPG. With VAG cars you had to make adjustments using VCDS but you could never really dial it in perfectly.
Nothing beats the manual calculation at the pump. Use the same method each time. I let the pump turn off automatically and then give it one more squeeze until it kicks off. Then I stop and record all my data. Use a system like that every time and you will create a consistent system to get accurate MPG over time.
If the computer on the vehicle is getting within 1 MPG then that is a pretty accurate trip computer.
Nothing beats the manual calculation at the pump. Use the same method each time. I let the pump turn off automatically and then give it one more squeeze until it kicks off. Then I stop and record all my data. Use a system like that every time and you will create a consistent system to get accurate MPG over time.
If the computer on the vehicle is getting within 1 MPG then that is a pretty accurate trip computer.
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More Turbo
Joined: Mar 2006
Posts: 582
Likes: 2
From: Eads, TN
This is a little off topic, but I have noticed a big difference in filling up the tank on my new F250 compared to my 2003. When I filled up the 2003 and let the gas handle cut itself off, diesel would spew over the filler neck and flow all over the outside paint. I had to get used to listen as I filled up at the pump; and when you could hear it getting close to being full, I had to baby the pump so that it would not over flow. There was a mod you could do to the tanks to help prevent that, but I never got around to doing it.
With my new truck, I let the pump cut itself off and no spewage. I'll try the method by Redrocker to get a more accurate measure each time.
With my new truck, I let the pump cut itself off and no spewage. I'll try the method by Redrocker to get a more accurate measure each time.
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Senior User
Joined: Dec 2016
Posts: 219
Likes: 1
Either method is within the statistical margin of error, but the computer is far, far more consistent than a hand calculation. If you're going to be comparing fuel mileage from one fill-up to the next, use the computer's numbers. Hand calculating has too many variables, including the density of the fuel based on temperature when pumping, whether or not you are on slight incline, decline, or level, and how accurate the station's pump are.
More Turbo
Joined: Oct 2016
Posts: 551
Likes: 39
This is a little off topic, but I have noticed a big difference in filling up the tank on my new F250 compared to my 2003. When I filled up the 2003 and let the gas handle cut itself off, diesel would spew over the filler neck and flow all over the outside paint. I had to get used to listen as I filled up at the pump; and when you could hear it getting close to being full, I had to baby the pump so that it would not over flow. There was a mod you could do to the tanks to help prevent that, but I never got around to doing it.
With my new truck, I let the pump cut itself off and no spewage. I'll try the method by Redrocker to get a more accurate measure each time.
With my new truck, I let the pump cut itself off and no spewage. I'll try the method by Redrocker to get a more accurate measure each time.
Senior User
Joined: Aug 2017
Posts: 196
Likes: 3
From: Colorado
1.0 mpg off first fill up, 1.0 mpg off 2nd fill up, .9 mpg off 3rd fill up, .6 mpg off 4th fill up so far for me. I try to do the same procedure each time, fill up til it clicks off, wait 15 seconds, top off. Level ground, no reason for more error really.
