How To Adjust Your Indicated Average Fuel Economy

[stresstest]

Awesome! @ RubyRed15GT you're the man!

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[Stangnut]

Got mine within 0.1 mpg. Thanks, again RubyRed15GT! Can't believe this isn't a sticky in the main forum. Especially with some of the useless, pointless, ridiculous stickies that are there now.

 

[GJarrett]

Ditto... mine was originally reading 6% high, but now with another 2,700+ miles on the meter and adjusting per this thread, it is dead on reading 24.3 mpg with an actual 24.3 mpg. Many thanks to the OP!

 

[chriseco]

Subbed so I don't forget about this once I get some more miles on my avg mpg

 

[ABS550]

Done! Mustang was a 950 and my 2013 Escape was a 980. (have been tracking them both since new) Thanks for the useful info!

 

[Coyote Red]

Great thread, I am coming from a 14 3.7 that got 30 hwy. My GT gets 22-24 hwy so I am happy. Aren't Texan's great thinkers!

 

[solodogg]

Old post, but with all of the fuel economy talk lately I figured this needed to be bumped back up. Mine read super high prior to calibration, but has been mostly dead on over the last 2 years after adjustment.

 

[Mustang_Lou]

Never saw this before … nice. Will adjust over the weekend.

 

[RichBrew]

I've been wanting to do this, but the steps for getting in to engineering test mode don't seem to work on 2019 with the digital dash. Anyone know how to do this?

 

[Intrepid175]

Thanks for your efforts!

Now if we can just figure out:
1. How to display the digital speedometer during normal driving. (i.e. not in the engineering test mode)
2. Show "instant" gas mileage, not just average.
3. Stop the horn from honking when you get out of the car while it's running.
4. Have the clock change with DST.
5. Have the radio turn off when you turn the car off instead of waiting until the door is opened.

Actually, I like that the radio stays on until I open the door. I wish it would stay on regardless of how long I sit there instead of shutting down automatically after a couple of minutes.

I just discovered this conversation. I'm looking forward making this adjustment in the morning!

 

[MakStang]

Nice thread! I will do this as well.

 

[Intrepid175]

Well, I made the adjustment. I've kept a fuel log on my Mustang ever since I took delivery. I write down date, mileage, gallons taken to fill up, and my calculated mpg followed by the computers calculated mpg in parenthesis. Turns out I've filled the car up 66 times. I added all the mpg numbers up and divided by 66. I was thinking I was averaging something between 1.2 and 1.5 mpg difference between my numbers and the computers. Turns out, overall, the difference was only 1 mpg. Anyway, I came up with a number of 957. I'm on my first tank of fuel so we'll see how it turns out. I'll run three tanks through it and report back. Stay tuned!

Drive Safe,
Steve R.

 

[florida _mel]

Well, I made the adjustment. I've kept a fuel log on my Mustang ever since I took delivery. I write down date, mileage, gallons taken to fill up, and my calculated mpg followed by the computers calculated mpg in parenthesis. Turns out I've filled the car up 66 times. I added all the mpg numbers up and divided by 66. I was thinking I was averaging something between 1.2 and 1.5 mpg difference between my numbers and the computers. Turns out, overall, the difference was only 1 mpg. Anyway, I came up with a number of 957. I'm on my first tank of fuel so we'll see how it turns out. I'll run three tanks through it and report back. Stay tuned!

Drive Safe,
Steve R.

Related to this adjustment, does it adjust the "miles to empty" or will it require different steps?

 

[Intrepid175]

Related to this adjustment, does it adjust the "miles to empty" or will it require different steps?

I'm pretty sure the miles to empty readout is calculated off the average mpg number. You get that adjusted right, the miles to empty should take care of itself. I just finished my first tank after making the adjustment. Before, the difference between the computer and my calculations was typically between 1 and 1.5 mpg. After that first tank, they were only 0.4 mpg off. I'll run three to four tanks through and see how the averages hold up and then adjust it a little at a time to see how it works out. Either way, it's much closer.

 

[Rash]

I did 10 fill-ups worth of calculations, them made the adjustment following the OPs instructions. Last two tanks have been only .1 mpg difference.

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