No Lifetime MPG value stored

[GPSMan]

2022 XLT Hybrid has no "Lifetime" MPG value stored.

(Your truck probably does not either.)

You can "reset to zero" your trip odometer and MPG info whenever you want. But what happens if you never press reset?

Others have shown the miles only tally up to 9999 then roll over to zero.

The MPG value does not "roll over" but it only holds the most recent 2500 miles of fuel data.

Data is "FIFO". First In - First Out. The oldest data is overwritten as you drive beyond 2500 miles. It is a "rolling average" not a true lifetime average (unless you have gone fewer than 2500 miles total).

Case Studied:

I drove 8427 miles on 210 gallons. (1000 of that was towing). This is 40.1 MPG true lifetime. But my "never reset meter" was displaying 47 MPG, because none of the towing was in the past 2500 miles and I have a very gentle commute route.

Then, at 8427 miles I towed a big trailer from California to Alaska and return. On this long towing trip, I got 18 MPG on paper, and my "never reset trip meter" displayed 19.0 MPG.

My true "lifetime" MPG is on paper:

13,788 miles / 495.9 gallons used which is 27.8 MPG true lifetime.

Of that, 6280 miles were towing.
(so I'm proud of the MPG)

Mathematics agrees with observations:

After returning home, removing the trailer, and going back to daily commute:

Never reset meter start: 19.0 MPG
Trip 2 reset to zero.
Drove 271 miles to and from work over two weeks.
271 miles averaged 49.0 MPG.

In 271 short miles (out of 14,000) the never reset meter increased from 19.0 MPG to 20.4 MPG.

My one-way trip to Alaska was 2540 miles. It was at the destination then did I notice my tank MPG (the one I reset) and my never reset MPG matched. I knew at that moment all my high MPG commute data had been overwritten

Using algebraic equations to solve for "what is size of trip meter" it came to 2418 miles.

Probably due to exact driving conditions this can vary a little. But it won't vary much.

Up to you if you want to round down and call your long term average 2400 miles. Or round up to 2500 miles, one-fourth of an oil change interval.

But the truck does not keep MPG data "forever".

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[GPSMan]

Q: When you add a trailer (or other big load) how long does it take for Miles to Empty to Adjust?

A: 250 Miles.


From the moment you start pulling a trailer, MTE will gradually decline. But it becomes accurate and reliable after 250 miles.

Same works in reverse. MTE will climb for the first 250 miles after you remove the trailer.

 

[MaveRichard]

You did the math. I knew that this was the case, but didn’t have this “extreme” data on both ends of the MPG spectrum to calculate it this accurately.

I reset “Trip 1” every tank. I keep “Trip 2” around knowing it is inaccurate. Maybe I should just use that for oil changes.

You had me beat(prior to Alaska trip) by .9 lifetime, 39.2MPG over 9609 miles. No way I will be able to keep this up in the winter though!

 

[MaveRichard]

What about Miles to Empty?

Well...

Interesting you brought this up, because I almost added it to my original comment.

Since I adjusted my AFE bias down 5%, my miles to empty is almost exactly 5% lower than it ends up by the end of the tank.

Sounds like you can either have an accurate MPG number on the dash or accurate Miles to Empty. Not both.

The Miles to Empty display is just a calculation based on the current MPG and how much has been used of the “13.8” gallon tank.

 

[commadorebob]

It makes sense. Your last 2,500 miles are more representative of your current driving conditions. 10,000 miles a year means your MPG is mainly reflective of the season you are driving in.

 

[GPSMan]

Interesting you brought this up, because I almost added it to my original comment.

Since I adjusted my AFE bias down 5%, my miles to empty is almost exactly 5% lower than it ends up by the end of the tank.

Sounds like you can either have an accurate MPG number on the dash or accurate Miles to Empty. Not both.

The Miles to Empty display is just a calculation based on the current MPG and how much has been used of the “13.8” gallon tank.

I haven't seen that. See #2 above though.

 

[Old Ford Guy]

2022 XLT Hybrid has no "Lifetime" MPG value stored.

(Your truck probably does not either.)

You can "reset to zero" your trip odometer and MPG info whenever you want. But what happens if you never press reset?

Others have shown the miles only tally up to 9999 then roll over to zero.

The MPG value does not "roll over" but it only holds the most recent 2500 miles of fuel data.

Data is "FIFO". First In - First Out. The oldest data is overwritten as you drive beyond 2500 miles. It is a "rolling average" not a true lifetime average (unless you have gone fewer than 2500 miles total).

Case Studied:

I drove 8427 miles on 210 gallons. (1000 of that was towing). This is 40.1 MPG true lifetime. But my "never reset meter" was displaying 47 MPG, because none of the towing was in the past 2500 miles and I have a very gentle commute route.

Then, at 8427 miles I towed a big trailer from California to Alaska and return. On this long towing trip, I got 18 MPG on paper, and my "never reset trip meter" displayed 19.0 MPG.

My true "lifetime" MPG is on paper:

13,788 miles / 495.9 gallons used which is 27.8 MPG true lifetime.

Of that, 6280 miles were towing.
(so I'm proud of the MPG)

Mathematics agrees with observations:

After returning home, removing the trailer, and going back to daily commute:

Never reset meter start: 19.0 MPG
Trip 2 reset to zero.
Drove 271 miles to and from work over two weeks.
271 miles averaged 49.0 MPG.

In 271 short miles (out of 14,000) the never reset meter increased from 19.0 MPG to 20.4 MPG.

My one-way trip to Alaska was 2540 miles. It was at the destination then did I notice my tank MPG (the one I reset) and my never reset MPG matched. I knew at that moment all my high MPG commute data had been overwritten

Using algebraic equations to solve for "what is size of trip meter" it came to 2418 miles.

Probably due to exact driving conditions this can vary a little. But it won't vary much.

Up to you if you want to round down and call your long term average 2400 miles. Or round up to 2500 miles, one-fourth of an oil change interval.

But the truck does not keep MPG data "forever".

great post and really informative research. thanks much Sir.

 

[MaveRichard]

Having MTE adjust on a much shorter timeframe is very logical so that it gives you a realistic estimate, based on recent data, how far you can go. It is very possible I am just seeing variance in the first/second half of the tank.

Before I filled up today my MTE was 112, I had driven 511 = 623 Miles. I filled up and it reads 570 MTE.

 

[GPSMan]

Before I filled up today my MTE was 112, I had driven 511 = 623 Miles. I filled up and it reads 570 MTE.

I've seen that, now that you were more specific. But at the time you filled up was needle at 1/8 or representative of the 112 remaining?

Also I think being on a slope affects things inversely of what's intuitive.
Pointing uphill, so liquid gas running away from the engine, the fuel gauge reads high. Sensor must be at rear of tank.

 

[MaveRichard]

I've seen that, now that you were more specific. But at the time you filled up was needle at 1/8 or representative of the 112 remaining?

This was right about 1/4, maybe just under. I didn’t take a picture. 11.2 gallons added.

13.8 - 11.2 = 2.6 gallons “remaining”

112/2.6 = 43.1

I did ~25 miles of highway driving today so it is very possible that I got 43 MPG for the last 250 miles. Just further evidence that the truck “thinks” it only has 13.8 gallons on board.

 

[GPSMan]

I've mathematically confirmed the 13.8 value is the value the computer uses by looking at aggregate data from 20 owners.

And by running past the "zero" mark have pumped in 15 gallons a couple of times and ran to actually the truck stopped once and pumped in 16.5 gallons.

I know what size tank is in a 2022 Hybrid Maverick.

 

[Old Ford Guy]

I've mathematically confirmed the 13.8 value is the value the computer uses by looking at aggregate data from 20 owners.

And by running past the "zero" mark have pumped in 15 gallons a couple of times and ran to actually the truck stopped once and pumped in 16.5 gallons.

I know what size tank is in a 2022 Hybrid Maverick.

i'm pretty sure that the system uses the 13.8 gal capacity figure for it's MTE calculation as well as how much remaining fuel is displayed on the fuel gage.
the actual physical capacity of the fuel tank IS larger than the manual would suggest.
one last thing, hybrids have a pressureized fuel system that needs a bit of 'air' in the tank(i dont know the exact amount) to operate as designed so 'over filling' the tank on a regular basis is not recommended.

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