cross-posted from: https://lemmy.world/post/22892955

The Prius Prime is a dual fuel vehicle, able to run 100% on Electric, or 100% on gasoline, or a computerized blend in-between. This presents me a great opportunity to be able to do a direct comparison with the same car of an EV engine vs an ICE engine.

  • Toyota computer claims 3.2mi-per-kwhr.

  • Kill-a-watt (https://en.wikipedia.org/wiki/Kill_A_Watt) claims 2.2mi-per-kwhr.

  • Additional 1.5% losses should be assumed in the wires if you wish. (120V drops down to 118V during charging, meaning 2V of the energy was lost due to the resistance of my home’s wires).

  • Level 1 charger at home (known to be less efficient).

  • Toyota computer claims 53miles-per-gallon (American Gallon).

  • I have not independently verified the gallon usage of my car.

  • 295 miles driven total, sometimes EV, sometimes Gasoline, sometimes both.

  • 30F to 40F (-1C to 4.5C) in my area this past week.

  • Winter-blend fuel.

  • 12.5miles per $electricity-dollar (17.1c / kw-hr home charging costs)

  • 17.1 miles per $gasoline-dollar ($3.10 per gallon last fillup).

If anyone has questions about my tests. The main takeaway is that L1 charging is so low in efficiency that gasoline in my area is cheaper than electricity. Obviously the price of gasoline and electricity varies significantly area-to-area, so feel free to use my numbers to calculate / simulate the costs in your area.

There is also substantial losses of efficiency due to cold weather, that is well acknowledged by the EV community. The Prius Prime (and most other EVs) will turn on a heater to keep the battery conditioned in the winter, spending precious electricity on battery-conditioning rather than miles. Gasoline engines do not have this problem and remain as efficient in the winter.


I originally wrote this post for /c/cars, but I feel like EVs come up often enough here on /c/technology that maybe you all would be interested in my tests as well.

  • Simulation6@sopuli.xyz
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    4 days ago

    I have a question about these dual fuel cars, gas has a shelf life and can mess up your engine if you let it sit for too long. Would this become an issue if you only make short, electric drives in the car?

    • vithigar
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      4 days ago

      The manual of mine specifically points this out and says that if you go three months without burning any fuel the engine will start being used until about a third of a tank is consumed.

    • dragontamer@lemmy.worldOP
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      4 days ago

      Yes but there is an easy solution. Just fill up with 2 gallons, rather than 10 gallons.

      Now you have the 100mi backup gasoline (why you bought a PHEV, right?), but still do EV every day. Every few months hit the HV button and burn off that fuel and fill up another 2 gallons.

      That being said: Prius Prime dual mode has 0-60 time of 6.6 seconds. When both engines are on your acceleration is amazing, on both low end 0-30 EV) and high end (ICE engine covers 30-70mph).

      So you want to be in auto mode (aka: use both engines mode) anyway for optimal driving experience.

      And now that I know that gasoline is cheaper in the winter anyway, maybe I push that ‘use both engine’ button more…


      If you ever need the 500mi gas tank for a long trip, just spend 5 minutes at a gas station. It’s not like our gas tanks are locked behind 20+ minute chargers or whatever.

    • lime!@feddit.nu
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      4 days ago

      most hybrids run the engine for a few minutes a month anyway, as a precaution. keeps it lubricated and sloshes the fuel around to prevent it from layering.

      also i don’t know how common this is but my car pressurises its tank to prevent offgassing, which apparently keeps the fuel good longer.

    • SupraMario@lemmy.world
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      4 days ago

      Gas does… but we’re talking a years before it’s going to damage anything. It loses its octane rating and can eventually start to gum up, but we’re talking years and years at that point.