38 mpg in 2010...confused

Discussion in 'Gen 3 Prius Main Forum' started by macmaster05, Dec 22, 2021.

  1. macmaster05

    macmaster05 Senor Member

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    My 2010 Prius (w/ 115k miles) has been on 17" FR-S wheels as long as I've owned this car and was showing 42 mpg on Trip A over the last 20,000 miles. I thought I could bring that up when I recently installed new Pirelli LRR tires about 300 miles ago. I never paid attention to mpg in this particular car as I've been a Prius owner so long I know Priuses will get 40+ no matter how you drive them. BUT, I just calculated my mpg for the first time and it was an abysmal 38 mpg after the first 311 miles on my new tires. Indicator showed 40.2 mpg. Does anybody know why? When I owned a Gen 2 I got 50mpg easily and my driving style hasn't changed much. There are a couple things I can think of such as (1) they're brand new tires (2) I haven't checked (inflated) the tire pressure yet to my ideal 40 psi and (3) I'm still running heavier 17" wheels, but all that shouldn't take my mpg under 40. I also read a thread about FR S wheels from 2013 here and those guys were claiming 46+ mpg. I'm pretty disappointed. Is it my car? Does being a high mileage oil burner have to do with any of this? NGL, if I can't fix this, it really makes me want to sell my car...

    Thanks!
     
    #1 macmaster05, Dec 22, 2021
    Last edited: Dec 22, 2021
  2. xliderider

    xliderider Senior Member

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    It's common to see a decrease in fuel efficiency with new tires. More tread equals heavier, stiffer tire.

    Posted via the PriusChat mobile app.
     
  3. macmaster05

    macmaster05 Senor Member

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    Just checked my air and all 4 tires are at a lousy 35 psi.
     
  4. OptimusPriustus

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    Isn’t that the recommended pressure. I don’t think your MPG issue is caused by tires. Suggest you check brake drag, air filter, egr..

    ps. My 2010 Prius with 17” OEM rims is doing something like 43MPG. Just had egr system cleaned and hoping MPG to improve. My brakes do not drag and filters are new
     
    #4 OptimusPriustus, Dec 22, 2021
    Last edited: Dec 22, 2021
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  5. bisco

    bisco cookie crumbler

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    the dash readout has always been optimistic, toyota wants happy customers, and spreading the love
     
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  6. OptimusPriustus

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    All manufacturers want that. Half a liter or even more per 100km. I dont understand why they were let to do that. New cars now have more accurate numbers. Maybe the WLTP or something forced them
     
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  7. abdullah arslan

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    I had the same thing (not the same tire but Michelin CrossClimate2), check the brakes. after replacing rear rotors and pads, MPG climbed from 38 to 45
     
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  8. macmaster05

    macmaster05 Senor Member

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    what priuschatter uses the recommended tire pressure. We all know we all like to overinflate slightly to hypermile, at least that was the case when I was more active on this forum 10 years ago, lol. Anyways I just pumped up psi to 40 and hoping for some improvement.
     
  9. AzusaPrius

    AzusaPrius Senior Member

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