I'm getting 34mg, plz help!

Discussion in 'Gen 3 Prius Fuel Economy' started by nzdice, May 8, 2018.

  1. nzdice

    nzdice New Member

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    I've been looking through the forums here about low gas mileage, but it seems like the majority of people who have complaints about this get 43mpg or 40mpg at least. 34mpg for a 2012 Prius seems very low. I don't know what to do here. I took it to a mechanic who said I have to take it to the dealer. I took it to the dealer, and they said it's going to cost $150 just for an inspection, and then if I get repairs afterwards they can't guarantee it will fix the issue. What should I do here?
     
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  2. Aluhex

    Aluhex New Member

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    Hey, I've been having the same issue. Usually get anywhere from 30-38 mpg, on average around 35mpg, I thought that it was due to something wrong with my car but I resetted the trip meter and hopped on the freeway, got up to 65-70 mph and turned on cruise control for about 10 minutes. That's when my mpg started hitting 50mpg. Which means that it's my driving style and not the car itself. I'm doing other things to try to increase MPG such as changing out the cabin/engine air filter and replacing the tires with the Goodyear Assurance Fuel Max which I'll set to 42psi front/40psi rear. I'm pretty sure it mainly comes down to driving style, you can search up gliding/coasting.
     
  3. bisco

    bisco cookie crumbler

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    welcome!
    we need some background please. how many miles on her?
    how long (time/miles) have you owned her? what tire make, model and pressure?
    how are you measuring mpg's?
    how many miles a day do you drive, and what length trips?
    when did you last clean/replace the air and cabin filters?
    this will get the ball rolling, and we can have you check some other things.
     
  4. MelonPrius

    MelonPrius Active Member

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    Aluhex, thanks for posting this. This is exactly the same advice I always give when someone is concerned about lower mpg. On an uncrowded highway using cruise control, one should hit 50+ mpg if driving alone. The cruise control is the important part as it takes the potential lead foot out of the equation.
     
  5. KeinoDoggy

    KeinoDoggy Member

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    Check to see if the rear brakes are dragging badly.
     
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  6. paprius4030

    paprius4030 My first Prius

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    I guess I'm strange LOL. I always get better mpg's on the highway when I DON'T use the cruise control. Especially when traffic is a little on the heavy side and you have to go like hell to keep up with everybody, that's when I get my best mpg's. I think it's because your always going up and down in speed, it's like forced pulse and glide.
     
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  7. Aluhex

    Aluhex New Member

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    No problem at all, I saw his post sitting here for a couple days and I recently figured out the solution myself. I'm sure questions like these come along every few days so hopefully they find their way here. For anyone reading, I'd suggest using cruise control on open roads at night while there's no traffic so you can maintain speed comfortably.
     
  8. bisco

    bisco cookie crumbler

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    hello?
     
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  9. Raytheeagle

    Raytheeagle Senior Member

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    Hit and run :whistle:?
     
  10. Lucifer

    Lucifer Senior Member

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    A 12, let me be blunt, the traction is 6 years old, get a new one, 1600$, 500$ labor, back to 50+mpg, and another five years.
     
  11. bisco

    bisco cookie crumbler

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    what is A 12? why would you replace a 6 year old traction battery without a code, isn't it under warranty?
     
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  12. MelonPrius

    MelonPrius Active Member

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    If you can beat cruise control, it's because you have a disciplined right foot. However, there are posters asking for advice on why their fuel economy is bad and the right foot can't automatically be ruled out as a culprit. Fortunately, it's a simple and cheap test.

    I know lead foots that skip cruise control, stick in the passing lane, drive way above the speed limit, tailgate the car in front of them, swerve from lane to lane as if they're playing Frogger, move their foot from the gas to the brake to the gas to the brake, etc... and wonder why they are way below EPA estimates.
     
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  13. nzdice

    nzdice New Member

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    Hey guys, thanks for all the help!

    Okay, so my car has 104,000 miles. I got it when it had 77000 miles, and this problem has been happening since it hit around 85,000 miles.

    I just got the tires replaced, as I thought that was the issue. GT Radaial Champiro Touring A/S. I think these tires are pretty bad, but this issue has been happening well before I got these. And my car has been driving very bumpy already so I don't really want to inflate them even more. But I think they are around 35psi.

    I measure mpg from clocking the miles per gas tank. Is there a better way to do this?

    The last mechanic I took it to said the air filter under the hood is completely fine.

    And I do drive for Uber/Lyft in Los Angeles (part time 15-30hrs/wk), so I know this can effect mpg, but still I would expect the least I would get would be 40/mpg.

    Also, the car has been riding very bumpy for the last 10k miles (and it still is after replacing the tires). 2 mechanics I took it too pushed down on the tail end of the car and immediately said I need to get the shocks replaced, but I thought they might have been jerking me around, so I took it to a few more mechanics (including the dealer), who said the shocks are fine and there's no leaking (and 1 mechanic told me shocks have nothing to do with mpg). Also, the dealer mentioned something about something under the back seat of the car being effected by Uber passengers constantly getting in an out; does this ring any bells?

    Also, for the past 6 months or so, I have been practicing better driving (gliding, etc...) and unless I'm still not driving well, there's been no improvement.

    Can the hybrid battery be slowly dying?
     
  14. MelonPrius

    MelonPrius Active Member

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    That's my guess, and luckily, you are still covered under warranty because you're in a CARB state. Just verify that the car is not from out of state nor has a salvage title.

    But something is wrong with the car, your driving style, or the driving conditions as the mpg is way too low. If you want to save yourself $150, first try Aluhex's advice on a round trip highway run on a warm engine at 70 mph or less. Set tripometer to measure mpg.

    Also, what were your ballpark mpg when you were between 77k and 85k miles? Did you have good fuel economy then?
     
  15. bisco

    bisco cookie crumbler

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    never heard of anything under the back seat being affected by people getting in and out. take it to a suspension shop and have them look everything over. you could easily need new struts, bushings, etc.
    the bumpy ride and mpg's are not related.

    if your dividing miles driven by gallons of gas, that's fine.
     
  16. bisco

    bisco cookie crumbler

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    have a mechanic lift her up and make sure none of the brakes are dragging.
     
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  17. nzdice

    nzdice New Member

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    Okay so I took Aluhex’s advice (thank you!) and drive on the highway with cruise control. I turned on the mpg (the thing that says “cons” right?) And after about 20 mins, it got to 46mpg. After I got off the highway it dropped down to 41. I have noticed that sometimes I am too hard on the gas, but the reason is that I feel the car is somewhat sluggish on the acceleration, and especially when going up hills. Maybe that’s just how the Prius handles, and hopefully its not the transmission. 41mpg is still pretty low, so I think something else is still the issue.
     
  18. MelonPrius

    MelonPrius Active Member

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    How far/long did you use cruise control and more importantly, did you use it for a round trip? RT is important because even a slight change in elevation can make a big difference in fuel economy. And what speed did you set your cruise at?

    Assuming that you drove by yourself and you made a 50 mile round trip highway trip, you should have gotten more than 46 mpg. That's why I'm asking these questions.
     
  19. Aluhex

    Aluhex New Member

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    You're getting 46mpg which isn't bad, I would say the target is 50-53mpg. So the deviation could be due to your tires (Low Rolling Resistance? I didn't look up if your tires are LRR). If you haven't changed out the cabin/engine air filter in the last year then you may consider changing it out. I think I read somewhere that it helps a bit, but I'm not sure myself. Either way its cheap to replace and easy to DIY.

    When you say the car is sluggish, are you in ECO/PWR or normal mode? The idea to increase mpg is to not use gas. Get up to speed using electricity and gas and maintain the speed by using little to no gas (keep it under the halfway mark on the hybrid indicator screen, 'ECO' should light up). The slightest press of the gas pedal will push it past the halfway mark. Especially if you are in Power mode. Using Eco (less than halfway) will also make you feel sluggish or a slight lag before acceleration kicks in.
     
  20. PutPutMobile

    PutPutMobile Senior Member

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    46 mpg is pretty good.. I drive like a maniac when accelerating from a full stop because I hate tailgaters. Then when I reach on a speed I want, I release the gas for 1 second then tap on it lightly. Pulse and Glide really works well... I get about 44 to 45 mpg by the way I drive now on ECO mode and I'm satisfied with it..

    Try to brake slowly before a full stop, It will increase your mpg while your hybrid battery regenerates. Braking hard will never get to increase mpg by .1 or .2 on your dashboard..

    The first 60-80 miles on your meter on a full tank is crucial. If you drive carefully with using mostly the electric side and driving on a flat road, you can get about 49-53 mpg easily.
     
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