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New to me Gen 3 is not living up to fuel economy expectations

Discussion in 'Gen 3 Prius Fuel Economy' started by VFerdman, Nov 27, 2024 at 11:06 AM.

  1. VFerdman

    VFerdman Senior Member

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    Hello, there, fellow Gen 3 owners and drivers. I have been (and still am) a very happy Gen 2 owner since 2017 and over 135K miles. My dear 2007 is getting long in the tooth with 310K miles and I have now bought a 2011 Gen 3 with only 120K miles and very good maintenance record from a person I know (they take very good care of their things). I have been driving this very clean Gen 3 for a few months now and am having hard time getting much more than 41 MPG. I do not hypermile and am not interested in "tips and tricks" to do that. I drive my Gen 2 like a normal car and I consider myself to be a fairly spirited driver. You can check my Fuely numbers for my Gen 2. It's 45 MPG over the last 7 years (I log every single fill up). I realize it's not as high as some here, but it's ok with me since I just drive this car as a car, not a hobby. So if I need to flog it to proerly and safely merge on the highway, I do it. I drive mostly country roads and once a week or so I make a highway trip to the big city (of Boston), which is about 200 miles round trip. This has been my pattern with Gen 2 and is also the same for the Gen 3. Yet, even if I try to be "good" with the gas pedal, I still struggle to get anything other than high 30's - low 40's MPG on this car. I realize that now that the temps are going low it's not going to do well, but I bought the car when the weather was ideal for good fuel economy, in the 60's 70's most of the time. Still poor fuel economy on this car. I like the car a lot. It's smooth, quiet and drives well, but about 10% worse on gas than my old Gen 2 with 310K miles and burning lots of oil. Could it be the tires? I run Nokian WR2 Gen 4 on the Gen 2. They are LRR. The Gen 3 has GoodYear Assurance WeatherReady (whatever those are). They are almost brand new and I will drive on them for now. I realize tires can effect fuel economy as much as 5%. I have not checked the spark plugs. Tire pressure is at 40psi. My driving style is the same as on Gen 2. I drive like normal and if I need to get out of my own way, I go ahead and step on that gas pedal. I have to work really hard to get anything lower than 45 mpg on the Gen 2 (in fall/spring weather). Usually it's closer to 50 mpg. But this Gen 3 struggles to break 40. So about 10% worse than an old Gen 2 with 310K miles. Is this the norm or I need to look for problems in this new to me car?

    Thank you all in advance!
     
  2. bisco

    bisco cookie crumbler

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    yes, tyres and pressure can play a part.

    did it get the full 120k service recommended by toyota from a dealer?

    gen 3 engine is a bit different unfortunately. you have the egr clogging and blown head gasket right around your mileage.
    throttle body cleaning may help.
    air filter
    dragging brakes
    12 volt battery
    hybrid battery
    etc
     
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  3. Mendel Leisk

    Mendel Leisk Book Cover Judge

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    How does it feel when you let off the gas? I know when we replaced our burnished Michelin Pilot HX MXM4 with Primacy MXM4, I could feel the extra drag. Both say "Green X", the LRR badge Michelin uses, but irregardless, mpg plummeted.
     
  4. VFerdman

    VFerdman Senior Member

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    It feels normal, whatever that is. Nothing of note. They feel like ok tires. I do not think they are officially LRR, though. Not sure about that, but I can not see an LRR mark on them. In any case, they are brand new in July, so I am stuck with them for now.

    Come spring I will clean the EGR cooler and do other Gen 3 things to it. I was really going to skip Gen 3, but Gen 4 is more expensive than I can afford at the time and also some of the design decisions in that generation of Prius are kind of deal breakers for me. Shiny reflective surfaces on the dash are just dangerous, not to mention ugly. Aesthetically I can live with the ugly duckling, but there is definitely a drop off in user experience even from Gen 2 to Gen 3, though Gen 3 still has a very sensibly designed UX (user experience). No shiny surfaces to distract and bother the driver, no huge screens and plenty of knobs and buttons for frequently used functions. I must be getting old, but the idea of the entire user interface relegated to a touch screen makes me not want to drive. That is, of course the whole point, I suppose, in transition to driver-less cars. I am totally fine with driver-less, but the in-between stage is terrible. Give me the knobs and buttons and levers to operate my vehicle or make it so as to not involve me at all.
     
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  5. Mendel Leisk

    Mendel Leisk Book Cover Judge

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    My lament too. Changing vent mode used to mean reaching down and adjusting a slider or dial, your eyes never needing to leave the road. Now you’ve got to find it’s button (in a row of identical buttons), and look down (away from the road) for a protracted time, tapping that button and trying to decipher the cycling LCD icons. Go to fast and you may go past it, have to start afresh. Progress…
     
  6. BiomedO1

    BiomedO1 Senior Member

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    You've got a bad case of mileage envy....
    Low to mid-40's is what's expected from an admitted spirited driver. Unfortunately, you really have to time and mash the pedal to avoid getting yourself killed - while trying to merge or turn left into on-coming traffic. That's the nature of this beast.
    If the car is properly maintained and serviced at regular prescribed intervals - there isn't much more you can do. Other than change your driving habits, which you stated your not willing to do.
    You can throw a bunch of money at the problem, but the math rarely pencils out and your never going to recoup the cost of those iffy adjustment, IMHO. But it's your car, give it a shot.

    Good Luck....
     
  7. VFerdman

    VFerdman Senior Member

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    The mileage envy I experience is to my own Gen 2 Prius with 310K miles. I am not a new Prius driver. Been driving my '07 since 2017 and averaging 45 MPG since then (I log every fuel up). I figure the later generation of Prius should go up in fuel economy, not down. Yet my experience with Gen 3 is about 10% decrease in fuel economy from Gen 2. I still think there are some underlying issues and I will eventually get back the 10%, but I may be wrong and it just is what it is. I am just disappointed that Gen 3 has worse fuel economy and some slightly worse design choices from Gen 2. Gen 2 really is the perfect Prius. I just wish they weren't too old to find a good one any more. My 2007 with 310K miles and getting 45 MPG with my style of driving is still on its original traction battery and seems to be going strong. I have rust problems on rockers and oil consumption on it, but it still runs and drives very well and I use it a lot without babying it. I do my own maintenance on it, which does not end up being a whole lot. It's a perfect car! The jury is out on Gen 3.
     
  8. Eddie25

    Eddie25 Active Member

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    Jack up the rear and make sure the wheels spin OK. The rear calipers in these cars are known to have issues.
     
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  9. VFerdman

    VFerdman Senior Member

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    I will definitely do that. It's just that the rear brakes were serviced by the dealer (on previous owner's watch) very recently. But I will most definitely test the rear wheels for spinning free. Thank you for the suggestion.
     
  10. bisco

    bisco cookie crumbler

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  11. ASRDogman

    ASRDogman Senior Member

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    Those tires are not lrr tires, just regular tires, that will lose you 5-10 mpg.

    Is the hybrid battery original? If so, perhaps the Prolong system will extend the life of it.
    And get you a few more mpg. If you need to replace it, get the Sodium battery. HUGE improvement.

    Time for spark plugs, engine coolant change, and might as well do the inverter coolant, super simple.
    And time for cleaning the egr system. And MAP and MAF sensor cleaning. With the proper cleaner.

    With such low mileage, the guide pins for the read calipers are probably sticking. Unless toyota actually
    cleaned them. And also clean the front ones.

     
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  12. Mendel Leisk

    Mendel Leisk Book Cover Judge

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    The rear (disk) brakes can be screwed up: there's a pin on the backing plate of pads that MUST fit in between the raised spokes on the caliper piston face. If it's not the brakes will drag, pads will get bevelled wear, and a swath of the rotor will go rusty from lack of contact. More info in a link in my signature (on a phone turn it landscape to see signature.
     
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  13. Mendel Leisk

    Mendel Leisk Book Cover Judge

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    And even with "LRR" (Low Rolling Resistance) tires, it's a mixed bag. I went from Michelin PIlots to Primacy, both had Michelin's "Green-X" badge on the sidewall (Michelin's LLR moniker), and mpg plummeted. It's taken a few years to climb out of that hole.
     
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  14. VFerdman

    VFerdman Senior Member

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    I am not going to touch the egr cooler and most under the hood stuff until spring. My hands don't work in the cold anymore. I live in New England. I will, however lift up the rear and feel the rear wheels. The rear brakes were just recently changed by a Toyota dealership, but we all know how that can be... The disks look like they are getting full pad coverageon the outside surfaces. Inside surfaces are a mystery at this point. The previous owner was fastidious, but not in any way a DIY owner. Took the car to the dealer for most things.

    Coolant was replaced, routine stuff done. Spark plugs were replaced , I think. It's hard to interpret the document on the Toyota Owners website. I will get to them in due time. In the meantime I will suffer with MPG envy :)
     
  15. ASRDogman

    ASRDogman Senior Member

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    Okay, but did they clean the guide pins? And the fronts?

     
  16. VFerdman

    VFerdman Senior Member

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    So I lifted each rear wheel off the ground and spun it to make sure rear wheels do not drag. They do not appear to have any more "drag" than on my 2007 Gen 2, which I also lifted to compare. I hear very slight rubbing sound from the pads, but the wheel goes around a few revs when I give it a good spin by hand. Also, the wear of the rotors is very uniform. We had rain overnight, so the rotors had a rusty patina from it and I took the car for a small ride to clear that out and when I came back and looked a the rotors, they were very nicely shiny and uniformly worn. I will probably check them closer in the spring, but at this time I would say they are not dragging.
     
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  17. rjparker

    rjparker Tu Humilde Sirviente

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    A hybrid battery failing is the common cause for much lower mpg. Normally about 5 mpg. It will lose mpg without a code but you may notice the engine runs more at stop lights.

    Spirited driving with the bigger gen3 engine - another 5 mpg. Extremely fast of the freeway - now your spirited driving increases to a 10 mpg penalty.

    So a weak battery and pushing it hard hurts at the gas station. But that is small potatoes compared to an blown engine which you should aggressively save for and map out sources in advance. Gen3 is less reliable than Prii before or since.

    PS. - Today was a milestone 200 mile trip down I-35. I saw more gen3s dead on the shoulder than breathing hard trying to keep up.
     
    #17 rjparker, Nov 29, 2024 at 11:51 PM
    Last edited: Nov 29, 2024 at 11:56 PM
  18. vvillovv

    vvillovv Senior Member

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    Hybrids are not regular cars. are they?
    If you drive a hybrid like a regular car expect to gas it up like a regular car and not post to fuely every time.
    Gen 3s have issue, you should have done some research before buying.
    If you like the car and don''t mind adding oil. that's wonderful. If you have problems with the car later you can't say that no one warned you about what to expect.
    Comparing it to your cream puff that's getting a bit long in the tooth of a Gen 2 is an exercise in futility. Take your pick of the two, it's like comparing your children to each other, we all do it, even if we shouldn't.
    Be prepared.
     
  19. ASRDogman

    ASRDogman Senior Member

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  20. VFerdman

    VFerdman Senior Member

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    I updated above. I lifted up the rear wheels and made sure they do not drag. That is all I got. I will probably order a Prolong harness for the battery as I already own the Prolong charger and discharger. The battery seems ok and reports about 65% life expectancy on Dr. Prius. It's about as good as my '07. Everything being equal, Gen 3 just seems to have worse fuel economy than Gen 2, which I did not expect. I thought Toyota was in the Prius line for fuel economy and despite bigger engine (and no improved performance from Gen 2) would provide improved fuel economy over Gen 2. Not the case in my very short sample.