does 2010 Prius' gas tank shrink in cool weather?

Discussion in 'Gen 3 Prius Fuel Economy' started by SUPERCOOLMAN, Oct 24, 2010.

  1. SUPERCOOLMAN

    SUPERCOOLMAN Junior Member

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    I got my 2010 prius earlier this week, so it's brand new. last week, fuel gaudge on my prius had 3 out of 9 bars disappeared and I had to fill it with about 2.6 G to fill up the tank to full. this week, 4 out of 9 bar disappeared meaing half of tank was empty, but I only need to fill it with 1.8 G to get a full tank. what's with this difference? does gas station just randomly calculate the amount of gas filled or 2010 Prius's gas tank shrinks in North California when temperature is just 16C/61F from 20C/68F? I'm 200% sure sure I drove way more mileage this week than last week. I can understand fuel efficiency improves as you get more milages on car, but I didn't expect gas tank to do that too.
     
  2. Paradox

    Paradox Prius Enthusiast / Moderator
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    The 2010 no longer has a bladder like the Gen II, so dare I say 'shrinkage' shouldn't be an issue anymore.

    Speed at which the fuel is going in, angle at which your car is parked at the station etc can affect when the handle clicks during a fill up.
     
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  3. Codyroo

    Codyroo Senior Member

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    The gas tank does not shrink on a 2010. Actually, the 2004 - 2009 had a bladder in the tank to limit gas vapor from the tank, the consequence of this was that it was difficult to assess how much gasoline was available for use.

    That is not the case here.

    You are focusing WAY too much attention on the pips. How many miles did you drive? How many gallons did you use/refuel? What was your calculated MPG's versus the displayed MPG's?

    PIP's are fairly meaningless, they give you a very rough idea of how much gasoline is in the tank. You'd be better off looking at your displayed MPG for the tank (after filling up, press the "trip" button on the steering wheel until the trip meter resets, you may have to toggle the "display" switch to get the right (HSI) display). If your car is averaging 45 mpg (displayed by the car), you can probably go 400-450 miles before filling it up.

    I don't track PIPs in my car, I have no idea if the first one disappears after 50 miles or 100 miles. I do know that when the last one starts "flashing" on my car, it means I have ~ 2 gallons of gasoline left in the car and I usually just drive and get gasoline at that point, no sense in running out.
     
  4. SUPERCOOLMAN

    SUPERCOOLMAN Junior Member

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    so the fuel PIP on 2010 Prius display is not meaningful until it flashes at only one bar left?
     
  5. Paradox

    Paradox Prius Enthusiast / Moderator
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    Just don't read into the pips. When you feel you're low enough you want to fill up, fill up. Don't worry about how much you fit each time with 4 pips, or 2 pips, or 7 pips etc.

    One thing that seems standard is when the last pip flashes, almost everyone can fit 1.9 gallons give or take a tenth or two, in their tank in the 2010.
     
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  6. fuzzy1

    fuzzy1 Senior Member

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    Mine has 10 bars, not 9.

    My top two bars are wild. The top one is highly variable, depending on the vagaries of the refill, including the sensitivity of the filling station pump shutoff and the slope of the parking pad. The next bar is typically short, and both bars frequently 'refill' for no good reason.

    Only after dropping to 7 bars does my gauge begin a semi-consistent 1-bar-per-gallon march down to the last bar. And any one bar can reappear at any time.

    The raw unfiltered, undamped fuel gauge reading displayed on a ScanGauge-II, while showing 0.1 gallon resolution, sloshes around by several gallons. Most, but not all, of this sloshing is filtered out by the dashboard gauge.

    This gauge is no worse than the analog needle gauges on my previous cars, and is better than several of them.
     
  7. bwilson4web

    bwilson4web i3 and Prime

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    It depends upon what you're after.

    With my wife's 2010 Prius, flash means there is ~2.1 gallons of gas remaining. I reset a trip meter and use the MPG and miles to figure out how much is left in the tank. This usually gives about 120 miles until all gas is gone . . . tested five times with a spare, 1 gallon can, in the back.

    As for the other pips, I don't really pay much attention to them. I like to see all of them lit after filling up. Otherwise, I don't care what they do until the last one begins to flash. Then I start planning to fill up.

    Bob Wilson
     
  8. Tideland Prius

    Tideland Prius Moderator of the North
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    A gas gauge in any car is just an indication of roughly how much fuel you have. It's not an absolute number (i.e. half tank = half a tank.. It really isn't). Most people only notice these things on a Prius because they actually start tracking mileage and consumption.

    IOW, I wouldn't put a strict number on each pip.
     
  9. SUPERCOOLMAN

    SUPERCOOLMAN Junior Member

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    I started with a full tank from dealer, and have filled 6.847 gallons (read from gas pump) in total with a full tank right now. car mileage is well over 400 miles(read from car) with 27 initial miles before I get this Prius. I've been driving in normal mode and have left auto AC/heat ON since I got my Prius. I guess my mileage is pretty good?

    thanks for everyone's explanations. this is my first car, so I'll probably have more questions in the future. please be patient with me :)
     
  10. qbee42

    qbee42 My other car is a boat

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    Part of the problem is the digital nature of the fuel pips. Since they are on a digital display and you can count them, people somehow assume they carry the accuracy associated with digital electronics.

    The problem is really on the other end. The fuel sensor is just a float, exactly like that found on any old car with an analog fuel gauge. As a result, the Prius fuel gauge is no more accurate or linear than that found on any ordinary car.

    Tom
     
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  11. bwilson4web

    bwilson4web i3 and Prime

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    I would recommend finding one of the web sites that record vehicle mileage and starting your log. The advantage is over time you'll be able to test different things and see the effects. If you're not sure, www. fueleconomy. gov is a good start since it also shared your mileage with the larger community.

    GOOD LUCK!
    Bob Wilson

    ps. Nice car to start with.
     
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