What has your experience been with the MPG Average function?

[Dave2018]

I haven't reset the average function on the Speedometer for over 6 months. I reset the trip meter after every fill up. The average MPG function seems to be limited to a certain number of miles. Does anyone know what that number is? I accidentially reset the average and now it's jumping around. I know that it does this after being reset, but how many miles does it need before it becomes stable?

 

[kurek]

I feel like it stabilizes around running time rather than miles but that is just a guess. That gauge is depressing and I don't look at it much

 

[Jrod]

I learned it's a lie'ometer.. I used to lead foot everywhere, filled up every 5 days, and my meter read 14.5ish. After a run in with Smokey a few months ago I began driving the speed limit everywhere. Since then I can go 7 days on the same commutes, and still have just under a 1/4 tank left at the end of the week. Meanwhile my lie'ometer only reads 15.5... In short, I don't trust it anymore..

 

[ram1500rsm]

I don't even pay attention to it.

 

[RoadRamblerNJ]

Nah, it's optimistic for sure. In my case, it usually reads 11.5 +/- 0.5 mpg. Hand calcs are usually 9-10 mpg depending on how much fun or frustration is comin' my way. This is in my '17 2500 Tradesman, 6.4, 4x4, 4.10's with MF cat back, K&N CAI, PC and my 42 yrs of North Jersey "driver's training". LOL.

 

[CamperMike]

It definitely is optimistic and only goes back for a few hundred miles I think. I always reset trip a but leave trip b alone. Considering trip b has 6000+ miles on it it moves around quite a bit. It usually says I'm getting 16.5-17mpg and real world is right around 16.

 

[mtnrider]

Have no idea how many miles it uses to calculate the average? All I know is mine is consistently 2-3mpg high compared to real hand calculated. (always has been). Wish I could calibrate the thing to be more realistic. Right now I just look at it and subtract 2.5 and that gets me pretty close.


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[Travelin Ram]

Based on my observations I agree with you, it varies too much to be average since the prior reset. It has to be average over a certain maximum distance. I’m guessing something like 50 or 100 miles. Maybe a call to customer support would yield that information?

I’m not too concerned with mpg as such, other than it’s a useful indication of vehicle performance issues. If it’s not in the typical range it’ll clue you in to start looking for the reason.

 

[Dave2018]

Ive been pretty happy with mine. The trip average is in the 26+ range and the avg mpg average is between 26 to a little over 27.4. i was thinking 50 to 100 miles myself too. On the highway it usually takes 3 or 4 miles to go up a tenth of a mile when the eco meter is showing pegged at 30.

 

[6.7CumminsDrvr]

Mine is pretty consistently 1.2mpg optimistic, every once in a while it’s dead on but not often. I use that in conjunction with the trip meter to gauge how well each tank is going..........if I get around 200 miles at half a tank I’m doing well.

 

[JayLeonard]

I never did a calculation on my own, just "assumed" the computer would be close. I do like the numbers however because it shows better than I got with my 05 V-6.
I may choose to remain ignorant

 

[Konrad]

@Dave2018 @kurek

Technically and mathematically, it does not "stabilize". As an average it is constantly changing, only the changes become slower with mileage and gallons burned. It also gets more accurate and closer to the real number. The more miles and gallons, the harder it gets to gain that .1 mpg (but it's also harder to lose it)


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[sandawilliams]

It definitely is optimistic and only goes back for a few hundred miles I think. I always reset trip a but leave trip b alone. Considering trip b has 6000+ miles on it it moves around quite a bit. It usually says I'm getting 16.5-17mpg and real world is right around 16.

That mpg reading is just a feel good gauge. Hand calculate and it will bring tears to your eyes. My last 6 mopars have all been the same.

 

[Dave2018]

@Dave2018 @kurek

Technically and mathematically, it does not "stabilize". As an average it is constantly changing, only the changes become slower with mileage and gallons burned. It also gets more accurate and closer to the real number

Yes! I believe its doing a rolling average. If i was a math wiz id be able to figure it out. Problem:. Constant speed of 60mph. Odometer shows a 3-4 mile interval between .1increase in average mpg. This seems true up to a high of 27.9. the eco meter is showing 30+ pegged onthe display. Can anyone solve for the number of miles the mpg is based on?

 

[CamperMike]

That mpg reading is just a feel good gauge. Hand calculate and it will bring tears to your eyes. My last 6 mopars have all been the same.

Yeah last Chrysler van and this truck both read around 4-5% higher than hand calculated.

 

[kohersh]

I think mine is fairly accurate reading an average of 14.5.
What annoys me is the fuel gague showing empty (for the 27gal std tank) when I still have 5 gallons in my optional 32 gal tank

 

[Dave2018]

Yes, I've seen that before here. The 32 gal tank option isn't addressed. Does anyone with a standard cab 8ft bed have this problem? They are supposed to come with the 32 gal tank stock.

 

[kurek]

@Dave2018 @kurek

Technically and mathematically, it does not "stabilize". As an average it is constantly changing, only the changes become slower with mileage and gallons burned. It also gets more accurate and closer to the real number. The more miles and gallons, the harder it gets to gain that .1 mpg (but it's also harder to lose it)


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It has to have a finite sample length, otherwise there would be nothing you could possibly do in one day to move the needle on a 50000+ mile average.

 

[RoadRamblerNJ]

@Dave2018 @kurek

Technically and mathematically, it does not "stabilize". As an average it is constantly changing, only the changes become slower with mileage and gallons burned. It also gets more accurate and closer to the real number. The more miles and gallons, the harder it gets to gain that .1 mpg (but it's also harder to lose it)


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Correct.
I know it starts over every time you reset it because I've done that and launched a quarter mile run pegged and it reads like 3mpg. Reset it again, drive smooth and easy and it reads way higher. As stated, it's an average, easy math.

 

[RoadRamblerNJ]

It has to have a finite sample length, otherwise there would be nothing you could possibly do in one day to move the needle on a 50000+ mile average.

Never let mine go that far.
Trip A is reset at every gas fill-up.
Trip B is reset at every oil change.
My "B" is much slower to change than the "A".