How accurate is the "avg mpg"?

[Emt1581]

Still waiting for my owners manual to come in the mail. Until then I haven't messed with the radio, computer, etc. other than to press OK to reset the trip each time I fill up.

On the 3hr drive home from the dealer I was getting 19-20mpg. The second and third tank yielded me 15-17mpg and my latest fillup has me at 10-11mpg.

I could understand if I was doing drastically different driving, routes, etc...but thus far it's a commuter/everyday use car with a bunch of city AND highway driving so I'm not understanding the differences in mpg that I'm seeing.

How accurate is this gauge and how can I boost the mpg's back to that 19-20 instead of 10-11?

Thanks

-Emt1581

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[Chameleon]

Please stop posting every numerous thread you make in general section.

Thanks

-Chameleon

 

[BmacIL]

Still waiting for my owners manual to come in the mail. Until then I haven't messed with the radio, computer, etc. other than to press OK to reset the trip each time I fill up.

On the 3hr drive home from the dealer I was getting 19-20mpg. The second and third tank yielded me 15-17mpg and my latest fillup has me at 10-11mpg.

I could understand if I was doing drastically different driving, routes, etc...but thus far it's a commuter/everyday use car with a bunch of city AND highway driving so I'm not understanding the differences in mpg that I'm seeing.

How accurate is this gauge and how can I boost the mpg's back to that 19-20 instead of 10-11?

Thanks

-Emt1581

Track 3-5 straight tanks, actual vs. the trip computer. Find the percentage difference. Then, put the car into engineering test mode (instructions below) and change the multiplier for MPG calculation by multiplying whatever it is at by your percentage (i.e. if you are seeing 19 actual vs. 20 calculated = 95%, multiply your current value by 0.95 and set it to the result of that). Look for AFE bias and you'll see a number of between 960 to 1000 displayed. So if it were 95%, and the current value is 980, you would multiply 980 by 0.95 = 931. I have found mine is the most consistently accurate between city and highway tanks at about 955 or so.

To go into test mode:
Before you start the car, hold the OK button on the steering wheel for a few seconds, and keep holding as it starts. You'll see a message that comes up in the cluster confirming you're in Engineering Test Mode.

 

[Stormtrooper5.0]

.

 

[yomamma219]

Did you check the secret manual compartment? I bought mine used and my dealer ordered me a manual even though I found out I had one in the compartment when I got home. Or is it just standard for them to order a manual? Mine was Used-CPO if that matters.

 

[Eisman]

Search button is your friend.
http://www.mustang6g.com/forums/search.php?searchid=5716695

 

[JCFoster]

Track 3-5 straight tanks, actual vs. the trip computer. Find the percentage difference. Then, put the car into engineering test mode (instructions below) and change the multiplier for MPG calculation by multiplying whatever it is at by your percentage (i.e. if you are seeing 19 actual vs. 20 calculated = 95%, multiply your current value by 0.95 and set it to the result of that). I forget what the actual parameter is called in the test mode, but it'll make sense and you'll see a number of between 960 to 1000 displayed. So if it were 95%, and the current value is 980, you would multiply 980 by 0.95 = 931. I have found mine is the most consistently accurate between city and highway tanks at about 955 or so.

To go into test mode:
Before you start the car, hold the OK button on the steering wheel for a few seconds, and keep holding as it starts. You'll see a message that comes up in the cluster confirming you're in Engineering Test Mode.

Does AFE bias sound right? It's the last option with the parameter set at 1000. Numbers are not my thing at finding percentages etc. My last road trip the indicated avg was 1.2-1.3 mpg high from actual on each tank. Using your assessment, I reset it at 955 and will see how it does if I'm in the right area.

 

[BmacIL]

Does AFE bias sound right? It's the last option with the parameter set at 1000. Numbers are not my thing at finding percentages etc. My last road trip the indicated avg was 1.2-1.3 mpg high from actual on each tank. Using your assessment, I reset it at 955 and will see how it does if I'm in the right area.

That's the one.

It reads a little pessimistic on the highway and just a tad optimistic for city. Either way, I'm within 0.1-0.3 mpg of actual consistently.

 

[MRose]

My results over the last year (2016 GTPP)

 

[Big Boss]

My experience with my focus and previous Ford's is that the computer is a little on the generous side.

 

[BmacIL]

My experience with my focus and previous Ford's is that the computer is a little on the generous side.

But you can easily fix that! See above.

 

[zxd9]

Check out this thread for adjusting your mpg. Mine is now within .5 mpg vs calculcated.

http://www.mustang6g.com/forums/showthread.php?t=67564

 

[Dkar26]

It's a Mustang...who cares ?

 

[FirstGT]

Um wouldn't it have been easier to hand jam the numbers instead of posting another thread on a very basic and common topic?

 

[Blk2015GT]

It's a Mustang...who cares ?

Only reason would be that the mpg readout affects the distance to empty. It's always nice if that is closer to accurate. Another 5 or 10 actual miles until empty would be nice to know in certain scenarios.

I otherwise agree who cares if you're getting 14 or 16mpg, will it make any difference?

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