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Discussion Starter · #1 ·
Bought car, driving 1600 miles home.

At next stop I was watching miles left to empty. Basically had it to where when we stopped for dinner based on miles left it would be 30 to empty. Left dinner, car died after about 5 miles. Yes I was heading to gas station which was about 2 miles furthur.

Next tank I decided to test if I had a brain fart or miles to empty is broke or misleading. See pic attached. I filled up with 15.1 gallons, calculated mpg, and did (18.5-15.1)*MPG

My calculation says I had about 115 miles to bone dry car stalling empty.

Trip computer was telling me (see pic) I had well over that to empty. Like 60 miles beyond running out.

So I guess it's a "the more you know" thing but somehow I always expected these things to err on the side of caution -- not tell you you have more than you do.
 

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I have a coworker with a 2015 Forester. Ran him dry and stranded on interstate with computer still saying 40 miles to go.

I fill up around the 80mark.


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Miles to empty is a suggestion not a hard and fast fact. My vehicles rarely get below half a tank. Costs just as much to keep it full as it does half full.
 

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I try to never let the tank get below 1/4 full for a few additional reasons:
1. Never know when you might have situation when you can't get gas or stuck in traffic long time
2. Fuel pump in tank benefits from being fully submerged all the time
As they say, your mileage may vary ;)
 

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2016 OB 3.6R - Carbide Gray
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Bought car, driving 1600 miles home.

At next stop I was watching miles left to empty. Basically had it to where when we stopped for dinner based on miles left it would be 30 to empty. Left dinner, car died after about 5 miles. Yes I was heading to gas station which was about 2 miles furthur.

Next tank I decided to test if I had a brain fart or miles to empty is broke or misleading. See pic attached. I filled up with 15.1 gallons, calculated mpg, and did (18.5-15.1)*MPG

My calculation says I had about 115 miles to bone dry car stalling empty.

Trip computer was telling me (see pic) I had well over that to empty. Like 60 miles beyond running out.

So I guess it's a "the more you know" thing but somehow I always expected these things to err on the side of caution -- not tell you you have more than you do.
You have a problem with the fuel pickup if you are only getting ~15 gallons per fill. I *average* filling mine up at 16.4 gallons. That has skewed slightly down after this weekend due to two fill-up under 12 gallons. My max fill is 18.16 gallons. I would take your car in and have Subaru drop this tank and see what's wrong.

Screenshots to show what I am talking about:
 

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Meh.
I has wagons.
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To be clear, you ran your Outback outta gas...not the other way around.
 

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2. Fuel pump in tank benefits from being fully submerged all the time
As they say, your mileage may vary ;)
Internet folklore.

If the fuel pump is pumping gas, its happy. Its good all the way to empty.

In the Bad Old Days when electric fuel pumps were first placed inside the gas tank management was too cheap to allow engineers to provide protection. When ignition was on, fuel pump was on and running whether or not the engine was running or whether there was gas in the tank. The pump motor spins much slower when it is immersed in gasoline. Gasoline also serves to lubricate the bearings and brushes. It doesn't take much to do the job.

You did know the fuel pump electric motor is not only submerged in gasoline but totally soaked? The pump pushes gasoline through the motor and its brushes and windings. Gasoline lubricates the motor bearings.

Today the fuel pump will run no longer than 30 seconds after ignition is turned on before the engine starts. If engine does not start, no fuel pump. If you run out of fuel the thing to do is fill up, turn ignition on, listen for fuel pump to run until it stops. Cycle ignition off and on again before attempting to start the engine. If it doesn't immediately start then cycle the ignition again, don't keep cranking. Continuing to try only runs the battery down on an engine which is not going to start because the fuel pump is off. Must cycle the ignition off/on to get another 30 seconds of fuel pump.
 

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Discussion Starter · #8 ·
Oh yes I never try pushing it I usually fill up near 1/4 tank at the min. It was just a long trip and we we're trying to get to a food stop and hotel and as it was estimating 30 to fill when we arrived ...

I figured ok that's about 1 gallon, plus whatever reserve as any car I've ever had "0 miles left" meant you had about a gallon give or take depending on the car.

So I'm thinking get there and 2 gallons or so left, get food, get gas, not cutting it close.
 

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Discussion Starter · #9 ·
You have a problem with the fuel pickup if you are only getting ~15 gallons per fill.
The 15.1 fill was me filling it up at 1/4 tank left when it was telling me I had 170 miles to empty.

I estimated if it took 15.1 that left me about 3.4, enough has to go about 105-115 miles, not 170
 

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Bought car, driving 1600 miles home.

At next stop I was watching miles left to empty. Basically had it to where when we stopped for dinner based on miles left it would be 30 to empty. Left dinner, car died after about 5 miles. Yes I was heading to gas station which was about 2 miles furthur.
There are several reasons why it could run out with a distance to empty (DTE) estimate of about 30 miles showing. A mis-calibrated fuel sensor or a problem with the fuel pickup location are possibilities, but not the only ones; other real possibilities are that conditions changed and your gas mileage dropped significantly soon before running out (did they?), or going up an incline made the last bit of fuel unreachable (or both).

At any rate, this is a good example of why you shouldn't push the envelope, especially in an unfamiliar vehicle.

Next tank I decided to test if I had a brain fart or miles to empty is broke or misleading. See pic attached. I filled up with 15.1 gallons, calculated mpg, and did (18.5-15.1)*MPG

My calculation says I had about 115 miles to bone dry car stalling empty.
Was your calculated mileage 33.8 MPG?

Did you put 15.1 gallons in at the point where that picture was taken, with the fuel gauge showing just over 1/4 tank on level ground? If so, that does seem like it may be reading high.

Was Trip B reset at the previous fill-up? If so, the displayed 34.7 MPG says you'd need 14.7 gallons to fill; those things often seem to run about 4% optimistic, which is consistent with your actual 15.1 gallons and also suggests that you didn't overfill to get 15.1 gal in there.

Trip computer was telling me (see pic) I had well over that to empty. Like 60 miles beyond running out.
The distance to empty calculation is based on a running average of recent fuel consumption. Your calculated MPG was based on 15.1 gallons. They could easily have been significantly different.

I don't know the details of the algorithm used, but it's likely either a running tally of fuel used in some fixed distance, or distance traveled for a given fixed fuel quantity. That is, a continually-updated measure fuel used in the last, say, 50 km, or continually-updated measure of distance traveled using the last, say, 5 liters. [Those quantities are guesses.] It also could be an average mileage over some interval of time [last half hour?]. I wish I knew.

The upshot is that the DTE estimator has no way of knowing what kind of mileage you're going to get for the remainder of the tank, only what you have gotten recently. Sometimes you will see DTE increasing as you drive if you changed from a sustained poor-MPG situation to a much better one.

So I guess it's a "the more you know" thing but somehow I always expected these things to err on the side of caution -- not tell you you have more than you do.
Now that you know that you can run out with 30 miles showing, you know to err on the side of caution. The flip side is "that thing is always pessimistic. I can go much further than it says..."

Know your car before you try to test its limits, and before taking any drastic action to "fix" something that may or may not be a problem. Run a few fill-ups and keep an eye on the numbers to see if there really is a problem before, say, having the tank dropped.

Good luck and enjoy your new car!
 

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Discussion Starter · #11 ·
Miles to empty is a suggestion not a hard and fast fact. My vehicles rarely get below half a tank. Costs just as much to keep it full as it does half full.
Yes I know this. But every car I've ever had before this the empty suggestion arrives well before empty happens. Not the other way around like this one.

Normally at home I never go below 1/4 and I fill up every time. Never could understand people who put in $5-10 a stop. Seems like a waste of time.
 

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Discussion Starter · #12 ·
So my question might be is this normal for Subaru/Outback?

That it suggests you'll be empty at like negative 2 gallons left, unlike other cars I've had where empty means hey it's close but there's maybe .5-1.5 gallons left in tank?

Telling me I have 170 to empty when it's really 110 to empty seems as though that's further off than just a regular old hey this isn't meant to be exact just a rough idea.

Do all your cars do the same?

Or is something installed cockeyed in my gas tank?
 

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If the fuel pump is pumping gas, its happy. Its good all the way to empty.
Quoted for truth. Modern fuel pumps are designed to be cooled (and lubricated) by the fuel flowing through them, not by the fuel they're submerged in.
 
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Both my cars are 2005-2009. However, I have "pushed it" staying local. I have often seen my miles-to-empty as ------yep, Zero.

That is after 30-miles-to-empty...I have never run out of gas in either car and any of the above situations. Something isn't right. The computer is certainly off.

Maybe this is Subru's "diesel gate". Over inflated mileage computers so we all think we are getting stellar mpg until you run out of gas. I say someone post they got 600 miles to a tank in their OB.

Now that there.... just ain't right.
 

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I'm still wondering if the Miles To Empty figure is affected when you have the dealer decrease the displayed mpg.

Some of us, myself included, had the dealer decrease it 4% which is about spot on perfect with the calculated mpg for most of my driving.
 
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... unlike other cars I've had ...
Your new Outback is not "other cars." Focus on the way it actually performs, not the way you expect it to perform. With any new vehicle, you need to use wider margins until you learn (from observation) how yours actually behaves under real-world conditions, with you at the controls.

Do all your cars do the same?

Or is something installed cockeyed in my gas tank?
The primary problem, IMO, is one of unrealistic expectations. As several others have posted, Distance-to-Empty (DTE) is an estimate of future performance based on recent conditions, not a guarantee.

Anecdotally, neither my wife nor I have ever run a tank dry in either our 2015 Legacy or 2016 Outback. We normally get between 400 and 500 miles per tank, so that serves as a rough cross-check on the DTE display. At ~1/4 tank on the gauge or 100 miles DTE I begin planning for a fuel stop, and if DTE drops below 50 miles or the low-fuel warning light illuminates I start looking for the next convenient gas station. Based on hand calculations, I have found the displayed DTE in our two vehicles generally to be accurate within +/-20 miles. YMMV.

FWIW, the best one-tank mileage I've ever achieved in our Legacy was 39.4 mpg (559 miles, 14.203 gallons). Immediately after refilling the tank, the onboard computer proudly displayed 780 miles DTE. I chose not to believe it, and after a few miles of driving DTE had dropped to a more reasonable ~550 miles.
 

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Discussion Starter · #17 ·
The primary problem, IMO, is one of unrealistic expectations. As several others have posted, Distance-to-Empty (DTE) is an estimate of future performance based on recent conditions, not a guarantee.
I know empty is an estimate. I know I shouldn't (and I don't in my other cars) attempt to run it to ZERO every time.

But I don't think wondering and inquiring here if it's normal Subaru behaviour for EMPTY in this car's computer to mean 2 gallons past running out is unrealistic.

I can adjust to it and not trust it to be the least bit accurate. But I don't think it's unrealistic for a new owner to to come here and ask if it's normal or something unique/maybe wrong with a new car.

I don't expect 0 to mean exactly 0, but for 0 to mean you ran out of gas 60 miles ago seems a little beyond "oh it's always off a little and just an estimate, don't expect it to be exact"
 

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So my question might be is this normal for Subaru/Outback?

That it suggests you'll be empty at like negative 2 gallons left, unlike other cars I've had where empty means hey it's close but there's maybe .5-1.5 gallons left in tank?

Telling me I have 170 to empty when it's really 110 to empty seems as though that's further off than just a regular old hey this isn't meant to be exact just a rough idea.

Do all your cars do the same?

Or is something installed cockeyed in my gas tank?
I generally don't fill up before the DTE goes 50 miles remaining. I can tally it up, I have log of every fill-up I have ever done over the last 45k miles (31k on this one, and 1xk on the previous one). I have approximately 85 fill records for this car and I don't think more than a dozen of those were less than 17-17.5 gallons.

That leads me to believe if you ran out that soon, something is wrong, or you wildly changed your driving pattern shortly before running out. I think Amm stated the dummy like comes on at 2.2 gallons of fuel remaining. He can correct me if I'm wrong, though.
 

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Both my cars are 2005-2009. However, I have "pushed it" staying local. I have often seen my miles-to-empty as ------yep, Zero.

That is after 30-miles-to-empty...I have never run out of gas in either car and any of the above situations. Something isn't right. The computer is certainly off.

Maybe this is Subru's "diesel gate". Over inflated mileage computers so we all think we are getting stellar mpg until you run out of gas. I say someone post they got 600 miles to a tank in their OB.

Now that there.... just ain't right.
I do this around town pretty consistently. Which is also why half of my fills are >17.5 gallons. Knocking on wood..... I have never ran out either.
 

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Discussion Starter · #20 ·
I generally don't fill up before the DTE goes 50 miles remaining. I can tally it up, I have log of every fill-up I have ever done over the last 45k miles (31k on this one, and 1xk on the previous one). I have approximately 85 fill records for this car and I don't think more than a dozen of those were less than 17-17.5 gallons.

That leads me to believe if you ran out that soon, something is wrong, or you wildly changed your driving pattern shortly before running out. I think Amm stated the dummy like comes on at 2.2 gallons of fuel remaining. He can correct me if I'm wrong, though.
At home I usually never go below 1/4 before filling.

On cross country trip run out event happened when it was estimating 30 to empty yes I had pulled over and was city driving to gas station. Though I didn't think twice as I figured 30 to empty + reserve would have meant a good 1.5-2 gallons left. Plenty to go 7 miles to gas. City driving portion was maybe 5 miles until stranded and calling AAA. That doesn't bother me, oh well, new car not used to gauge.

But on my test run where it showed 170 to empty that was a fill up, drive 500+ miles, see 170 to empty and 1/4 tank left, pull straight into gas station, fill, calculate I had about 3.4 gallons left and would run out in 105-115

The second one where I was testing DTE computer bothers me as that was an overestimate of 2 gallons or so more than I had. And at time it was estimating I was getting a little over 34mpg (hand calc was 33.7) so it wasn't the mpg estimate being off that threw it off that much.

 
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