Bad mpg on 2011 prius

Discussion in 'Gen 3 Prius Fuel Economy' started by DungHo, Jan 22, 2020.

  1. DungHo

    DungHo New Member

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    I have just bought a 200k miles prius for a few weeks. Before I bought, my mechanic checked everything was okay except for some door lock problems. I have just change the oil and the oil filter, 12V battery was changed 2 week prior by the dealer but my car got 43.5 avg mpg on the dashboard trip. The Eco mode seem can't improve it at all. Do you guy know what else to check ?
     
  2. Pluggo

    Pluggo Active Member

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    Welcome to the group and congratulations on your Prius purchase. The first thing to check would be your tire pressures to make sure they're at least up to the suggested numbers printed inside the driver's door. The informal consensus seems to be that 40-42 psi works well. As for Eco mode, it changes how the car responds to the pedal but otherwise does not change fuel economy under any given load condition. Finally, before you get too concerned about fuel economy, verify your number the old fashioned way with pencil and paper after each fillup. At the end of the day, that's the only number you can really trust.
     
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  3. jerrymildred

    jerrymildred Senior Member

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    Welcome. @Pluggo gave great advice.

    Another huge factor is braking. If you brake like most drivers (at the last moment) that throws away a ton of gasoline. You spend good money on that gas, so when you see the light change to red start coasting or gliding if traffic permits and you're far enough away from the stop to get some free travel. Not gliding or regenerating is directly converting gas to heat and brake dust. It's an even bigger effect than how you accelerate.
     
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  4. bisco

    bisco cookie crumbler

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    welcome!
    you bought a car with 200k on the clock. the mechanic has no idea how warn out most of it is.

    40+ mpg is excellent, enjoy!
     
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  5. AzWxGuy

    AzWxGuy Weather Guy

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    All of what has already been said, and it is very likely that the change-out of the 12V battery has reset the performance curves the vehicle has "learned" since the last battery reset. A couple weeks and a more familiar value should return.
     
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  6. DungHo

    DungHo New Member

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    Thank everyone. Also, I hit a curb very hard so most of my undercover gone, the tire and wheels are still ok. I will gey them replaced soon. Do anyone have some clue about hidden damage for that hit?
     
  7. RMB

    RMB Senior Member

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    Winter and cooler temps will decrease fuel economy. Since you mentioned you only have it for a few weeks, just keep driving and observe. Also, driving conditions and habit are also major factors in getting good mpg.
     
  8. jerrymildred

    jerrymildred Senior Member

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    Most likely, your alignment got seriously whopperjawed from the curb hit. Might even have some bent parts, so you'd be smart to get the alignment checked out to protect your new tires.
     
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  9. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    Are you mechanically DIY inclined? The sand-pounder with 3rd gen with that amount of miles is carbon clogging of the EGR (Exhaust Gas Recirculation) circuit and intake manifold. By 200K miles you're flirting with head gasket failure.

    It sucks, but it is what it is. Have a watch, the relevant @NutzAboutBolts videos, linked here:

    Nutz About Bolts Prius Maintenance Videos | PriusChat

    In particular:

    14. Throttle body cleaning
    15. PCV valve replacement
    16. EGR pipe cleaning
    17. EGR Cooler Removal/Cleaning (See thread for more details)
    24. Cleaning intake manifold
    25. Oil Catch Can Installation
     
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  10. Frank1234

    Frank1234 Junior Member

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    When calculating the mpg the old fashion way nobody say this or a less I haven’t see anyone saying it, when you filling you tank up if you fill in a different gas pump you car can take more or less gas so you have to fill up in the same pump to get a accurate calculation.
     
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