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2015 Outback 2.5i Premium pzev - Red
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278 Posts
Discussion Starter · #1 ·
Scanned the threads and there isn't any recent post on the OB lifetime mpg.

Anyone ever find out if there is any fix / adjustment?

My lifetime average is now in the low 40s (better than the Prius V I looked at before buying the OB) . I have a little over 14K on the car. Of course I've never had a tank anywhere near that. I keep manual records and my spreadsheet (and fuelly agrees) says my lifetime is about 29.3. I know each tank claims a couple mpg high but the lifetime is now about 30% higher than reality.
 

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Premium Member
2015 Legacy 3.6R ES, 2014 Forester Touring ES, 2005 Jeep Liberty Limited
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3,243 Posts
Just get the latest HU update.

Laughing at Oneself and with Others is Good for the Soul
 

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'15 Outback 2.5i Premium
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2,590 Posts
Have they fixed the lifetime MPG problem?

It's already too late for me to get a completely accurate lifetime measurement, and as a computer geek I find the flawed system entertaining. I'm trying to characterize, by reverse engineering, what the error(s) is (are). There seems to be two problems: at some point the system stops accumulating fuel used, so the "lifetime MPG" increases linearly with distance. Sometime later it also stops accumulating distance traveled, so the "lifetime MPG" doesn't change at all. It appears to stop counting fuel use at 1024 liters, which makes a certain amount of sense, since that's a nice round number in binary. I'm less sure about the distance. Maybe it's 32,768 km, which would also make sense for the same reason, but i'm less sure about that. I'm already on my second "linearly increasing" phase after an intentional reset 1024 liters ago, so we'll see.
 

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2018 Dark Blue Outback 3.6R Touring arrived 8/31/2017
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343 Posts
Have they fixed the lifetime MPG problem?

It's already too late for me to get a completely accurate lifetime measurement, and as a computer geek I find the flawed system entertaining. I'm trying to characterize, by reverse engineering, what the error(s) is (are). There seems to be two problems: at some point the system stops accumulating fuel used, so the "lifetime MPG" increases linearly with distance. Sometime later it also stops accumulating distance traveled, so the "lifetime MPG" doesn't change at all. It appears to stop counting fuel use at 1024 liters, which makes a certain amount of sense, since that's a nice round number in binary. I'm less sure about the distance. Maybe it's 32,768 km, which would also make sense for the same reason, but i'm less sure about that. I'm already on my second "linearly increasing" phase after an intentional reset 1024 liters ago, so we'll see.
There are 3.78 liters per US gallon: unless there's a major difference in firmware between a US and Canadian-sold car, I'd expect you can change units easily. It'd be interesting to see if changing units cleared data, or at least we find the same weird error converted over, Andy see if there's a preferred unit of measure (I'd guess metric)
 
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