Am I doing something wrong?

Discussion in 'Gen 3 Prius Fuel Economy' started by Sheba, May 21, 2015.

  1. JimN

    JimN Let the games begin!

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    Given the details I would expect calculated fuel economy in the mid to high 40's.

    At 119 miles is the gas gauge down 2 or 3 pips? I'd buy gas just to see if 2 1/2 to 3 gallons could be pumped.

    Are you always stopping at the same gas station and using the same pump? Perhaps the pump is off. I would try a different station for a tank or two.

    Is the parking brake partially engaged?
     
  2. SageBrush

    SageBrush Senior Member

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    Fair thought.
    That would be really rare, but possible.
     
  3. Sheba

    Sheba New Member

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    All three fill ups have been at different gas stations, and different brands also. I am already down several pips, yes.
     
  4. CR94

    CR94 Senior Member

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    That's part of your problem.
     
  5. fuzzy1

    fuzzy1 Senior Member

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    Wow. What was the displayed MPG for the 32 mpg tank? If it was also 45-ish, that discrepancy between the displayed and the pump calculated MPG is completely out of line. The difference should be closer to 5%, and certainly less than 10% when averaged over multiple fillups.

    The displayed figure is quite reasonable, but the pump calculation is not, so I vote with the earlier response of a leak. Absent miscalculation or fuel pump fraud, somehow fuel is disappearing without being burned in the engine.

    Is any fuel leaking on the ground when parked? Is there any fuel smell around the car or engine compartment at the end of your trip? Does the gas door show any signs of theft or tampering, or does it not close securely to prevent opening without use of the inside lever?
    Don't bother calculating at your very first fillup. The driving and fill history before that is unknown, the previous fill may not have been to the top. Start at the second fillup, using the miles driven after the first fillup.
    This should be checked soon, as low pressure will sap MPG. But they would have to be dangerously low to cause your pump calculation, and cannot cause the pump vs display difference you see.

    Until the missing fuel mystery is resolved, everything else in this questionnaire is small stuff.
     
    #25 fuzzy1, May 21, 2015
    Last edited: May 21, 2015
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  6. Former Member 68813

    Former Member 68813 Senior Member

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    RE: "05 Pontiac Sunfire. 2.2L 4 cyl automatic. 19-21 mpg average"
    EPA for that car is 25 (21/31). this is the new calculation method that is close to the real life.
    the OP got 20% below EPA. using the same metrics, 40 mpg would be expected in prius.
    the indicated 45mpg is on the mark, my wife has a similar commute and she gets that.

    there must be something wrong with the car. since it should be covered by warranty, dealership should be able to do a MPG check. gasoline leak makes most sense, but it should be obvious to detect (smell).
     
  7. GrumpyCabbie

    GrumpyCabbie Senior Member

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    I do not know. At a steady 80 mph I could easily get 55 mpg UK or 45 mpg US. To be getting 25 mpg out of a Prius means the car is faulty or the owner is using for track days. It's almost impossible to get that sort of economy (or lack of) otherwise.
     
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  8. The Electric Me

    The Electric Me Go Speed Go!

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    Of all the responses this is the only one I would call a "Semi-Red Flag". But I don't believe it could be causing the horrible MPG the OP seems to be getting.

    Personally, I spend almost no time warming up The Prius. Unless my commute was such that I almost immediately hit the freeway? I think just starting the Prius and "regular" driving IS the best way to warm up The Prius.

    But I hardly think a minute or two of idling would cause the MPG numbers the OP appears to be getting.

    That's my feeling.

    Also hard to believe that a fuel leak could be happening at the level it would have to be happening and not leave evidence.

    I keep defaulting to the idea that it seems to be such a perplexing problem the car just needs to be checked out. Because it's either the car, or "Operator Error" in the form of miscalculations.
     
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  9. Sheba

    Sheba New Member

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    Thank you to everyone for all the replies and suggestions! I have already talked to my dealer and set up a service day to get the car checked out. Unfortunately I live several hundred miles away from my dealer so it's not going to happen this week, but it is still under warranty so that's good! :)
     
  10. GrumpyCabbie

    GrumpyCabbie Senior Member

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    I wonder, the OP says they've only just purchased the car. Are they, or someone else who's driving it, not switching it off correctly when they park it up?

    It's been previously reported by many new owners not familiar with keyless entry, that they're just getting out of the car and leaving it in Ready. If that's the case, then the car will be switching the engine on and off for the duration of the time it's parked up which would then give the ridiculously low mpg average.

    It just seems very very strange for a 2011 car to be getting such low fuel economy. Even ex taxis with 300k+ miles still get good economy. I'm sure I recall that cars with failing 12v's and even failing HV batteries get better than 25 mpg.
     
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  11. The Electric Me

    The Electric Me Go Speed Go!

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    I think the OP is doing the right thing. Just keep eliminating possibilities. Eventually what IS causing the abnormally low fuel economy will reveal itself.

    Assuming the calculations are accurate, and also assuming it's not something like the vehicle is being accidentally kept ON, then getting it checked out at the dealership is a good idea.

    I never really thought of the idea that someone's MPG would plummet if they weren't shutting the Prius off properly or for some reason The Prius wasn't staying shut off. I suppose that IS a possibility.

    I guess my greatest concern is hoping the dealership service department is competent, and does a thorough job of actually trying to identify a problem.

    I hate to say it, but modern "service" today has de-evolved to a point where it seem's they can't or won't do much beyond Oil Changes and Tire Rotations unless there is a "Code" to guide them.

    I think this might take some detective work, and I hope they are up to it.

    To the OP I would ask, have you tried to "Force It" to get good gas mileage.
    By that I mean, right after fill up, resetting the trip computer ( I use Trip Computer A ) then going on a longer drive at steady moderate speed over a flat surface? I mean 55-65 mph?

    My experience with my Gen 3, is that if I fill up and then immediately end up on the freeway on a longer drive? The MPG will reach 50 or better in the Spring, Summer and Late Fall.

    If for just a test you fill and go on a slight road trip--freeway not stop and go or around town, and the MPG still stays abysmal? I think at the least it would or should prove you have some problem happening somewhere. Outside of eventually learning some hypermiling techniques there really is no "trick" to getting Hybrid gas mileage from The Prius.

    I was getting 50+ mpg, on highway/freeway road trips of average speeds between 55-65 mph, without applying anything but the accelerator and brakes as needed. If this Prius cannot do this? Something is rotten in HSD land.
     
  12. SageBrush

    SageBrush Senior Member

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    If that was the problem the displayed MPG would match the calculated.
     
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  13. Former Member 68813

    Former Member 68813 Senior Member

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    what location in florida is hundreds of miles from a dealer? is it florida keys? if so, maybe the gas is somehow boiling away?
     
  14. Sheba

    Sheba New Member

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    I live 29 miles away from "A" dealer. However, I purchased the car at one a lot farther away.
     
  15. Sheba

    Sheba New Member

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    This was the very first question the dealership asked me when I called them about it. Apparently it really is a common issue! I've been turning off the car all the way, but as quiet as it is I can definitely understand how someone might forget!
     
  16. Markee

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    I just traded up about a week ago my 2010 Level 3 with 60k miles for a 2013 Level 4 with 15k miles .
    My first tank full didn't look to good i was only able to get 300miles out of it I'm already almost done with the second take full and its looking about the same something don't feel right the 2010 always got me at-least 400miles a tank full

    Can someone point me the procedure to get me into maintenance mode on 2010+ vehicles ?
     
  17. qdllc

    qdllc Senior Member

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    How do you NOT turn a Prius off correctly? It's a button for Heaven's sake! The alternative is to leave it on, and I think an alarm will sound if you take the fob out of the car while it's still on. The only way that'd not happen is if you leave the fob in the car, but wouldn't the illuminated instrument display be a dead giveaway?
     
  18. Sheba

    Sheba New Member

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    I've never tried it to see what would happen so I'm not sure. I do know my dealer m mentioned that it's happened more than once to new owners.

    I curious how much the mpg drops from idling though, I would think that since the car isn't moving it would run mostly on battery all night.
     
  19. Former Member 68813

    Former Member 68813 Senior Member

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    you know you can service it at any dealer, right?
     
  20. fuzzy1

    fuzzy1 Senior Member

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    It is easy to test, the car should emit several warning beeps as you leave. I'm not sure what happens if you try to lock it, but suspect it should refuse to lock, also with several warning beeps.

    The traction battery is not large enough to supply the 'idle' electric load all night. It will slowly drain to two bars, then the engine must fire up occasionally to recharge it one or two bars. But the engine will be off 90%+ of the time.

    But I doubt this is happening. As Sagebrush already pointed out, it would clobber the display mpg too.

    After writing most of my earlier reply, I realized that you didn't provide a pump calculation MPG and a dashboard displayed MPG for the very same tank. I.e. the 45.1 displayed figure is on the current tank, but the 32 mpg calculation was for the previous tank. We need both figures over the very same tank and set of miles.
     
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