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How many gallons to fill up your tank after the warning beep?

Discussion in 'Gen III 2010+ Prius Main Forum' started by hptsang, Oct 31, 2009.

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  1. hptsang

    hptsang Member

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    Today I finally have my chance to fill up my first tank. I ran for 462 miles , with one bar flashing after the beep and the computer shows 16 miles left for the rest of the tank. I went to the gas station to fill it up and only took me 9.66 gallons to fill it up to full. I thought it would take at least 11 gallons to fill it up since from the data it seems like I only have a gallon or less left in the car. Is that mean I will still be able to run 100 miles after the computer shows 0?
  2. fuzzy1

    fuzzy1 Senior Member

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    Your fill sounds about right. Mine takes about 9.5 at the warning beep.

    Bob Wilson intentionally runs out of fuel for sport. Somewhere around here is the very long thread where he first reports his tank calibration, along with the results of actually running it dry.
  3. spiderman

    spiderman wretched

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    Yup... fudge factor to make SURE you don't run the car out of gas. Mine usually takes 9.2 - 9.5 at fill up (0 miles to empty).
  4. pekinkaid

    pekinkaid Member

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    Beep and flashing pip = 9.4 gallons, twice for me.
  5. jburns

    jburns Senior Senior Member

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    Lotta fudge.

    I think this two gallon reserve is left over from years of low mileage cars. Back in the day if you got 15 MPG in a family car you were doing good. That would give you a 30 mile reserve after the gauge approached empty. Completely reasonable. This same two gallon reserve in the Prius gives you about 100 miles. Way more than necessary.
  6. bwilson4web

    bwilson4web 03 and 10 Prius

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    My testing to fuel exhaustion indicates there is 2.1 gallons remaining when FLASH starts. Because there is no indication when the last of the gas is gone, I do not recommend running completely out of gas.

    When the engine finally runs out of gas, the car switches to traction battery power without any driver notice. If you are driving faster than 46 mph, the MPG indicator will suddenly show 100 MPG and the traction battery SOC will start to drop. If running under 46 mph, such transitions can occur and may not be noticed until the traction battery is so low that all power is lost and the "power steering" error light comes on. At that point, the car can only roll to a stop.

    When FLASH starts, I reset the current trip meter and make sure to fill up before the 2 gallons is burned up. If I'm planning to run out of gas, I'll put a 1 gallon spare can in the back and monitor the display a little closer.

    Bob Wilson
    3 people like this.
  7. mjv

    mjv New Member

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    I've been using the Miles to Empty feature (first vehicle that had one) and was surprised when you would supposedly be running out of gas and still have two gallons left, I would think that one is plenty given the MPG performance of the vehicle. What surprises me is that when stopping at an intersection I had 9 miles to empty. When I started moving again, I have 0 miles to empty! I can usually go approximately 20-30 miles without an issue, but I think I will start using the trip meter just to document how many miles I go.
  8. madelinesonja

    madelinesonja Junior Member

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    The owner's manual says that when the lowest pip starts flashing, there is a reserve of about 1.6 gallons remaining. My first two tanks, I filled up pretty much immediately once the pip started, and I got about 9.5 gallons when I filled up. Today was my third fill, and I went about 50-60 miles after it started flashing (yesterday), and it took 10.25 gallons.
  9. DickPhillips

    DickPhillips Junior Member

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    I've wondered how much fuel it will actually take to fill the tank after the auto-shutoff of the pump. My wife's VW diesel powered New Beetle will take a good gallon and a half but very slowly as that stuff really seems to foam up. Maybe the best bet, if it doesn't take much after the initial shutoff to full, is to let the auto thing happen with the pump and then just round up to the next "even" money amount. If this is done consistently it might lead to a pretty constant level of fuel in the filled tank.

    I've only got about 2100 miles on mine at this point so haven't filled it many times yet. Still learning about the car- a lot.
  10. loobie

    loobie Loobie

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    golly, my 2007 prius used to take 9.5 gallons of gas... now it only takes 7.5 gallons. weird. the mph has not changed (around 47+).

    anyone else experience this?
  11. Teakwood

    Teakwood Member

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    I had the same experience, and had the same thoughts.
    Seems like that is the way that it is.
  12. ETC(SS)

    ETC(SS) Aspiring Hypocommuter.

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    About 9.4 gallons here, if I fill up within about 10 miles of the beep.
    I call the car 'full' at the first pump shut-off.
  13. Codyroo

    Codyroo Senior Member

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    Do a search in the Gen II fuel mileage forum and use the keyword "bladder". You'll get quite an education as to why you don't get as much gas into your tank in the winter as opposed to the summer.



    to the OP, yes, when the beep goes off, you usually have ~ 2 gallons of gas left in the car. It's to minimize the likelyhood of running out of gas (since you have about 80 - 120 miles of range left to find a gas station).
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  14. rrolff

    rrolff Prius Surgeon

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    The well documented answer to the post is very specific to Gen III (different from II).

    You have 1.9 gallons left after the beeps (thanks to the very famous ??????? - who tested this and doc'd it well-- do the search).

    I always set a trip when the beep occurs - at - you can go 70 miles safely (or course - look at your mileage - I get 45). Since I started this ideology (takes time to fill), I've never put in more than 11.3 gallons....

    When I fill, after it is full, I press the pump once more (seems to be the preferred method to not overfill - yet makes sure the car is full to a given point).
  15. dtuite

    dtuite Silverback

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    I finally got to that point on a long trip this winter. Same results as everybody else. It's nice to know you have that much headroom. Now the trick is not to get cocky.
  16. Lsegovic

    Lsegovic New Member

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    I always drive 10 miles after shows "0" on miles to pump station! I pump around 9.5 gallons!! Now I know I still have like 50 miles left on reserve! NICE ! If the gasoline prices go to 4 bucks like they say we will tart saving big time in comparison with non hybrid vehicles!
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