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Why is the Corolla hybrid's hwy mpg so high?

Discussion in 'Toyota Hybrids and EVs' started by bcretman, Aug 14, 2020.

  1. bcretman

    bcretman Junior Member

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    A non-hybrid gets 38 mpg vs 52 for the hybrid version. Shouldn't the mpg be about the same since the battery is not used on the hwy?
     
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    The engine itself in the hybrid version is modified over the standard engine even though the basics are the same.

    1. The engine runs on the Atkinson cycle rather than the Otto cycle. This gives it more efficiency at the expense of power (so you'll notice in the specification sheet, the hybrid engine output is lower than the gas version). The idea is that the hybrid system will offset that loss will additional power and torque from the battery and electric motors.
    2. The hybrid has Active Grille Shutters that will close over 60km/h to reduce drag and improve aerodynamics
    3. The hybrid runs on smaller and narrower 195/65R15 wheels and tyres vs. the gas models 16"-18" (except the base Corolla L which also uses the same 15" size but on heavier steel rims with wheel covers rather than lightweight alloys with wheel covers on the hybrid)
    4. The hybrid most likely also uses ultra low rolling resistance tyres. The others use just regular touring tyres or sportier ones in the XSE models and SE with Upgrade Package or Nightshade Edition
    5. An exhaust heat recovery system and cooled exhaust gas recirculation system help with getting the engine up the operating temperature faster (EHRS) and also keep the engine cool by using recycled cooled exhaust gas (EGR) instead of gasoline. The EGR also helps reduce emissions.

    Also, the battery is sorta used on the highway even though the engine is on over 90% of the time. Note that any time you let go of the accelerator or go downhill, the engine shuts off and you're in EV mode. Any time you brake to slow down for traffic or enter a construction zone, you're in EV mode. Also, the battery helps balance the engine power so the engine can rev at the most efficient rpm (and if it ends up producing excess power, it'll send some to the battery to store). When you go up an incline on the highway, the battery can also assist, which means the engine doesn't have to produce more power, thus using less fuel.
     
  3. bcretman

    bcretman Junior Member

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    Thanks for your detailed explanation!
     
  4. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    All those little twitches on the pedal that used to cause more gas to go down the hole are now just taking out brief loans from the battery, paid back almost immediately when your foot un-twitches.

    Run that unhybrid Corolla on cruise control for a few hours and the effects of computer control (vs. twitchy foot) will let you blow past that 38mpg. That would be a fairer comparison to the hybrid version, since the fuel flow in a Toyota hybrid is always under computer control.
     
    #4 Leadfoot J. McCoalroller, Aug 15, 2020
    Last edited: Aug 15, 2020
  5. Trollbait

    Trollbait It's a D&D thing

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    There is a module that plugs into the accelerator pedal that filters out those foot twitches.
     
  6. alanclarkeau

    alanclarkeau Senior Member

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    Go for a drive on the highway, then check the % of EV (ie battery) use, and it'll be somewhere between 20 and 45%, depending on traffic and topography - and your speed.

    There are a lot of other differences between Hybrid and Conventional (whether it be Camry, RAV4 or Corolla) - including tyres and engines. The engine has considerably higher efficiency (Atkinson cycle) due to a number of factors. On a run, my PRIUS has given these figures:
    upload_2020-8-15_23-7-26.png .

    My previous FOCUS Diesel would have averaged about 4.8 l/100km, for those trips - my wife's FOCUS Petrol more like 7.5-8 l/100km.
     
  7. priusman09

    priusman09 I used to be a TDI

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    The statement about hybrids that “a hybrid is not as efficient on the highway” has been made as a blanket comment over all hybrids. The Toyota hybrid system is more efficient that other manufacturers at highway speeds. Honda’s system is a good example of that. Alex on Autos did a real time comparison between the CRV Hybrid and the RAV4 Hybrid and there was a significant loss for the CRV at highway speeds where it was falling short of the epa estimates while the RAV4 actually exceeded the higher epa mpg estimates. That has also been my experience in over 300,000 miles of driving 2 different Prius. I always think it is interesting when people look at epa mpg city and hybrid estimates and say well the corolla gas gets 38 mpg hwy......which is almost the same as the hybrid. While In real time the car gets on a daily basis numbers a lot closer to the 31 city mpg estimates. It has been my experience with regular cars (Non hybrid) that one rarely get the highway figures except on those few strictly highway runs on vacation. While my experience with the Toyota hybrids are getting the 50+ mpg continually city and highway.
     
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  8. Mendel Leisk

    Mendel Leisk EGR Fanatic

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  9. Tideland Prius

    Tideland Prius Moderator of the North
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    Yup. In the last generation Corolla (a 2014 to be exact), I managed to get:

    3.9L/100km at 60km/h (60mpg at 40mph)
    4.7L/100km at 80km/h (50mpg at 50mph)
    5.5L/100km at 100km/h (42.7mpg at 62mph)

    with an LE on 16" alloys with a CVT with the CC set.

    A Gen 4 will beat those as it'll be in EV mode at 60km/h, probably 3.7-4.0L/100km at 80km/h and 4.1L/100km at 100km/h. Our 2016 Touring with the 17" alloys got 4.3L/100km driving down I-5 (70mph limit) round trip.

    Both the regular Corolla and Corolla Hybrid should beat their EPA ratings if you drive judiciously. Heck, you can get 4.2L/100km (56mpg) out of a 2019 RAV4 Hybrid (round trip 200km/125 miles on a highway with a 100km/h/62 mph limit).
     
  10. John321

    John321 Senior Member

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    Many people feel the Toyota Corolla is one of the most utilitarian and best cars in the world. We owned a 1992 4 door regular Toyota Corolla for almost 10 years. One of the very best cars I ever owned. With the birth of our youngest we had to get a larger vehicle and I hated to let that vehicle go. Reliable, economically priced and good fuel economy it checked all the boxes for a small family.
     
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  11. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Sedan? I'm hooked on hatchbacks now, more utility.
     
  12. John321

    John321 Senior Member

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    I agree 100%. I had never owned a hatchback until we bought our 2004 Sienna van and 2008 Prius. I have only owned hatchbacks since then.
     
  13. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Once you learn that "station wagon" and "hatchback" are equivalent but for scale, you begin to see it.

    Honestly, moving from an old-generation smallbody Outback wagon to a Prius c was a cinch. Had a v been available we might not have even noticed the difference apart from the ground clearance.
     
  14. bcretman

    bcretman Junior Member

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    The hatchback on our Volt was a major selling point, along with being able to drive EV mode 99% of the time. Strongly considered the Prius prime but it ended up being more expensive with less fed/provincial EV grants. Volt is not as efficient on the hwy, likely due to the battery's weight, best I've achieved is 3.7L/100km, avg 4.5.

    There is some very detailed info on the inner workings of the prius/prime transaxle at:
     
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  15. fuzzy1

    fuzzy1 Senior Member

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    That hasn't been my experience, even back in the late 20th Century when the same car would get even higher EPA numbers than now. EPA scale has shifted downwards multiple times.

    Though numerous speed limits have risen significantly since then, reducing the MPGs people actually get on any given car. Those who tend to drive faster than 60-65 mph won't get my MPG numbers.
     
  16. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Yeah no kidding.

    In keeping with recent examples, our other two recent family cars (Subaru Outback Turbo and Hyundai Accent) would both achieve somewhat better than EPA with the twitchy foot and both got >15% better than highway EPA when run with cruise control. Sometimes more.