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2020-159 HR in CO
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40 Posts
Discussion Starter #1
I'm wondering if you have found the trip MPG trip reading to be accurate. On my last tank of gas (mostly highway miles), it said I was averaging 18.1 MPG which I thought was decent considering I was driving through the mountains. My own estimate on MPG for the tank was lower, somewhere between 15-16 MPG.
 

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2019 159 High Top - White, of course!
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306 Posts
I keep track of mine on Fuelio which calculates by amount of fuel and mileage, and states 16.37 MPG. I have never reset one of my trip meters, which says lifetime fuel economy is 17.1 MPG. 8300 miles so far.
 

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2019 118" Silver
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940 Posts
My 2019 has almost 25K miles on it and overall the computer has been within one mpg most of the time I check it, making it the most accurate of any vehicle I've had. Sometimes it reads lower, sometimes higher, but usually a bit higher (i.e. - real world slightly lower). Most of the variation occurs primarily due to not getting it completely full every time, which seems to be part of the nature of these beasts.
 

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2014, 138WB, High Roof, Gas, SW MT
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2,072 Posts
On my van, the trip computer is about 0.5 MPG optimistic. But, this will vary with your particular van and tires.

To check the accuracy, you have to do several tanks of gas -- particularly on the PM, which is hard to fillup to exactly the same level each time.

Gary
 

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2014 Promaster 1500, 118" wheelbase, high roof, 3.6L gas
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4 Posts
On my van, the trip computer is about 0.5 MPG optimistic. But, this will vary with your particular van and tires.

To check the accuracy, you have to do several tanks of gas -- particularly on the PM, which is hard to fillup to exactly the same level each time.

Gary
I recently completed a 10,000 mile trip through western US and another 7,000 mile trip in the southeast.
Both trips averaged about 17 mpg and matched fairly well, what was displayed as average trip mpg on my dashboard.
 

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I keep a detailed spreadsheet of all my gas fill-ups and also include the van computer data in my spreadsheet. At about 41,000 miles, my cumulative hand calculated average is 17.48 MPG and the van computer cumulative total is 18.1 MPG. Individual tank fills can vary by as much as 2 or 3 MPG but the average is about .6 MPG
 

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2020-159 HR in CO
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40 Posts
Discussion Starter #8
I keep a detailed spreadsheet of all my gas fill-ups and also include the van computer data in my spreadsheet. At about 41,000 miles, my cumulative hand calculated average is 17.48 MPG and the van computer cumulative total is 18.1 MPG. Individual tank fills can vary by as much as 2 or 3 MPG but the average is about .6 MPG
Nice! And thanks for confirming my suspicions about the van computer being generous.
 

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2020 159 HR
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54 Posts
I tallied miles and gallons filled when I first picked up the van (580 mile trip), and then again on a 3,200 mile road trip. I found the trip computer to be within .1mpg of my own results on the first, and spot on over the longer road trip.

As an aside - my speedometer currently reads within one mph of my GPS; that's with pretty much brand new tires. I would expect that to diverge a bit as the tires wear down. Speedometer and odometer are fed from the same sensor and depend on an assumption of wheel circumference - which seems to be pretty spot on now with new tires, and likely to diverge a bit later. So I would expect my mpg calculation based on the odometer to become a bit pessimistic in time.
 

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2019 159 High Top - White, of course!
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306 Posts
I assume that the PM dash display computes MPG by the pulse width of the fuel injectors time the flow rate of the injectors, and the distance traveled by the odometer. That SHOULD be pretty accurate. Most cars/trucks are not however. My PM is the most accurate of any vehicle I have ever owned.
 

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2014, 138WB, High Roof, Gas, SW MT
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2,072 Posts
The PM actually uses its airflow sensor combined with the fuel - air ratio it is trying to maintain to estimate MPG.
Does not seem like it would be to accurate, but it does pretty well.

Gary
 
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