Does anyone have more miles on their 392 than I do?

[Uncommon Sense]

My I am approaching 40k miles on my 22XR. It is a daily driver. The bulk of the miles though comes from a couple of 1500 mile road trips a year. The jeep has been pretty reliable. Only issues so far have been the rear diff sensor and battery needing replacing.

 

[Overkill]

Are you checking the accuracy of the MPG dash readout by doing some manual calculations at fill-up time? Those dashboard "lie-o-meters" are notorious for reading high. Mine reads about 1 mpg high, but some are much farther off.
Also note that the manual calcualtions can be off, as you can "top off" the tank to somewhat different levels each time. The best way to do it over th course of at least 5 fill-ups. Take your total miles driven in that 5 fill-ups and divide by the total gallons of the 5 fill-ups. Don't re-set the lie-o-meter in between fill-ups. Do a cumulative run for at least 5 tanks, and compare the lie-o-meter to the manual calculations.

I completely agree with tracking more fill-ups. I've used an Excel spreadsheet since the first fill-up to track all of mine. At the top is the overall miles per gallon average.

 

[Captain Overkill]

I completely agree with tracking more fill-ups. I've used an Excel spreadsheet since the first fill-up to track all of mine. At the top is the overall miles per gallon average.

View attachment 45682

That is some detailed tracking. Good job. Have you compared your calculated numbers to what the dashboard "lie-o-meter" says what you are getting for MPG? It seems that on every vehicle the dashboard ones read high. ...Hence my calling those things "lie-o-meters'.

 

[CAMEL2R]

I bought my '23 with 6K mikes on it. A year and half later as a daily driver and it's just shy of 40K. I don't keep track of my fuel costs...I live in Commifornia, it's high, done.

 

[Overkill]

That is some detailed tracking. Good job. Have you compared your calculated numbers to what the dashboard "lie-o-meter" says what you are getting for MPG? It seems that on every vehicle the dashboard ones read high. ...Hence my calling those things "lie-o-meters'.

Yeah, the internal computer is normally about a half gallon per mile or slightly more off on mine. Like that last entry has 15.489 MPG and the vehicle was reporting 16.1 MPG.

 

[CAMEL2R]

Yeah, the internal computer is normally about a half gallon per mile or slightly more off on mine. Like that last entry has 15.489 MPG and the vehicle was reporting 16.1 MPG.

If you have a Tazer, you can dial in the tire size to get closer...in theory.

 

[Captain Overkill]

Yeah, the internal computer is normally about a half gallon per mile or slightly more off on mine. Like that last entry has 15.489 MPG and the vehicle was reporting 16.1 MPG.

Yours is more accurate than mine. Off by 0.5 or 0.6 mpg isn't too bad. My lie-o-meter reads high by about 0.9 to 1.0 mpg. I need to do more comparisons, as it is still fairly new with less than 1,600 miles on it.

 

[Captain Overkill]

If you have a Tazer, you can dial in the tire size to get closer...in theory.

Setting the right tire size helps, but ii's not just a tire size discrepancy thing. Those lie-o-meters read high even if the tire size is dialed in exact. I'm guessing they use some sort of fuel flow meter, and for whatever reason, those meters must miss some of the fuel going through them. So, they think you are using less fuel than you really are.

 

[CAMEL2R]

Setting the right tire size helps, but ii's not just a tire size discrepancy thing. Those lie-o-meters read high even if the tire size is dialed in exact. I'm guessing they use some sort of fuel flow meter, and for whatever reason, those meters must miss some of the fuel going through them. So, they think you are using less fuel than you really are.

Yeah, I figured there was more at play.

 

[Overkill]

Yours is more accurate than mine. Off by 0.5 or 0.6 mpg isn't too bad. My lie-o-meter reads high by about 0.9 to 1.0 mpg. I need to do more comparisons, as it is still fairly new with less than 1,600 miles on it.

Mine was off about 1 MPG for a while. It has started to get dialed in a little better lately.

 

[Overkill]

Setting the right tire size helps, but ii's not just a tire size discrepancy thing. Those lie-o-meters read high even if the tire size is dialed in exact. I'm guessing they use some sort of fuel flow meter, and for whatever reason, those meters must miss some of the fuel going through them. So, they think you are using less fuel than you really are.

I always figured they were using a calculation based upon how long the injectors are opened and really just guessing how much fuel passes in that time instead of an actual flow meter. That's the only thing that I could think of to justify why the internal computer is off. Like maybe the calculation isn't accounting for the slight amount of lower flow on the ramp from closed to full open and full open to closed. Who knows for sure though. I had also heard someone say it was basing the MPG over the last 100 miles. But without someone that actual programmed the computer (or someone hacks on to it), the world will never know.

 

[guruman]

I always figured they were using a calculation based upon how long the injectors are opened and really just guessing how much fuel passes in that time instead of an actual flow meter. That's the only thing that I could think of to justify why the internal computer is off. Like maybe the calculation isn't accounting for the slight amount of lower flow on the ramp from closed to full open and full open to closed. Who knows for sure though. I had also heard someone say it was basing the MPG over the last 100 miles. But without someone that actual programmed the computer (or someone hacks on to it), the world will never know.

The '23 manual actually states the average is since the last reset. Whether it's true or not, IDK. I've never reset mine.

 

[Overkill]

The '23 manual actually states the average is since the last reset. Whether it's true or not, IDK. I've never reset mine.

View attachment 45705

I read that as meaning for what it is displaying, but not the calculation itself. But, l have noticed that it starts off where it was at when I reset the trip meter. So if it is using that for the calculation, then it would be for the last 250ish miles for me normally. I haven't reset the overall average screen on this 392, but did on my last one since it was used when I got it and that started the MPG at 14.1 if I remember correctly. So if it is the overall average feeding the calculation, mine has been for ~12,000 miles.

 

[XRecon]

Are you checking the accuracy of the MPG dash readout by doing some manual calculations at fill-up time? Those dashboard "lie-o-meters" are notorious for reading high. Mine reads about 1 mpg high, but some are much farther off.
Also note that the manual calcualtions can be off, as you can "top off" the tank to somewhat different levels each time. The best way to do it over th course of at least 5 fill-ups. Take your total miles driven in that 5 fill-ups and divide by the total gallons of the 5 fill-ups. Don't re-set the lie-o-meter in between fill-ups. Do a cumulative run for at least 5 tanks, and compare the lie-o-meter to the manual calculations.

I don't really care about what mpg that I'm getting. The thread is about who can possibly have more miles on their 392 than I have. If I really wanted to know my mpg, you are right about how to do the calculations.