Prime SE owners: anyone driven to empty ?

Discussion in 'Gen 5 Prius Main Forum' started by Templeton, Jan 13, 2025 at 6:43 PM.

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  1. KMO

    KMO Senior Member

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    In the G5 low fuel comes on with some range left, and some fuel gauge bar remaining. Range indicator continues counting down. When range would become zero, it changes to "Refuel". And that seems to coincide with the fuel gauge becoming totally empty.
     
    #21 KMO, Jan 14, 2025 at 11:31 AM
  2. Gokhan

    Gokhan Senior Member

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    In my 2021 Prius Prime Limited, the HEV range left after the orange fuel sign comes on is well over 100 miles. I get about 70 mpg, and the orange fuel sign comes on with more than two gallons left. So, in my case, it is at least about 150 miles.

    My drive-to-empty (DTE) range displayed after refueling is lately about 726 miles. My actual HEV range should be around 800 miles. On top of that, I get close to 40 miles of a BEV range—it would definitely come handy if you accidentally ran out of fuel.
     
    #22 Gokhan, Jan 14, 2025 at 1:12 PM
  3. Trollbait

    Trollbait It's a D&D thing

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    Toyota could easily changed how it worked since my 2016 Camry, though I wonder if there are regional differences. Then the Rav4 PHV came out in 2019/20, what does it have?
     
    #23 Trollbait, Jan 14, 2025 at 1:16 PM
  4. bisco

    bisco cookie crumbler

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    In our first long trip with our new 24 hycam, i discovered that the range was less than our previous generation.
    After driving on reserve in unfamiliar territory at night, I decided to fuel up sooner this year.
    I won’t make that mistake again, it’s unnerving
     
    #24 bisco, Jan 14, 2025 at 1:39 PM
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  5. Gokhan

    Gokhan Senior Member

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    How much fuel did you have left? Did the car still run?
     
    #25 Gokhan, Jan 14, 2025 at 1:57 PM
  6. Templeton

    Templeton Junior Member

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    Yes, they said it went all the way to zero.

    Because the GOMs on rav4 primes will go all the way to zero on the 'HV miles remaining' display. Then, if you keep on driving, the display blanks out with a " - - " in the display. But the posters in the threads just kept track of the HV miles driven beyond the '0 miles' with their trip meters. At least one guy was able to go over 100 miles past that until the engine quit.

    So, my question, is: if you do this with a prius prime, how far can you go on gasoline (until the car reverts to EV mode)?
     
    #26 Templeton, Jan 14, 2025 at 2:03 PM
  7. Gokhan

    Gokhan Senior Member

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    Again, Gen 4 and Gen 5 are identical cars for most practical purposes, and I get over 100 miles (well over 100 miles with my driving style) after the orange light comes on in my 2021 Prius Prime Limited. If someone also got over 100 miles in his Gen 5, I believe that.
     
    #27 Gokhan, Jan 14, 2025 at 2:30 PM
  8. Templeton

    Templeton Junior Member

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    Actually, the 100 miles beyond the 'zero miles' indication that I read about was in a Rav4 prime, not a prius prime. But you think that a gen5 prius prime will go another 100 miles after the GOM indicates 'zero miles'? In your gen4, how many miles does your GOM indicate when your orange light goes on? Do you know if the fuel tank in your gen4 prime is identical in shape and capacity to the fuel tank in a gen5 prime?

    Has anyone actually tried this test (driven in HV until the engine stops because of a lack of gas) in a gen5 prius prime?
     
    #28 Templeton, Jan 14, 2025 at 2:43 PM
  9. Gokhan

    Gokhan Senior Member

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    The official fuel tank capacity for Gen 4 PHEV and Gen 5 PHEV are 43 L (11.4 gal) and 40 L (10.6 gal), respectively.

    I am not sure if DTE shows zero when the orange light comes on in my Gen 4 PHEV. I am guessing it still shows some miles.

    The only way to actually know what is going on in Gen 5 PHEV is to test it. You don't need to drive the car until you run out of gas. Drive it until the orange light comes on, record the odometer, and fuel it up to full tank with automatic pump cutoff with the car on a slight downward slope. Then, you will see how much fuel and, hence, how much range left in the car using the 10.6-gal capacity. It doesn't have to be accurate to 0.1 gallons. You can do the same when DTE becomes zero or simply check the odometer when DTE becomes zero and when the orange light comes on. In my Gen 4 PHEV, DTE will become zero with still about one or two gallons or so of fuel left, but I didn't check the exact amount.
     
    #29 Gokhan, Jan 14, 2025 at 2:58 PM
  10. Templeton

    Templeton Junior Member

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    This would be a good approach, except that it assumes that all of the fuel in a fuel tank is usable.

    But it is not. Every fuel tank has some amount of unusable fuel.
     
    #30 Templeton, Jan 14, 2025 at 3:02 PM
  11. Gokhan

    Gokhan Senior Member

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    True, but probably a very small amount. If you can get an estimate within 0.3 gallons, it should be good enough.
     
    #31 Gokhan, Jan 14, 2025 at 3:21 PM
  12. Templeton

    Templeton Junior Member

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    Your method would not yield an estimate of unusable fuel. To get an estimate of unusable fuel, one would need to either open up a fuel tank and examine it (or maybe get CAD files of it) or run the fuel pump until it no longer is able to draw fuel from the tank.

    There is no certainty that the unusable fuel in a prius is a very small amount. I agree that it is not likely to be an enormous amount, but in other small vehicles unusable fuel can vary greatly depending on the size, shape, and design of the fuel tank and also the location of the fuel pump intake.
     
    #32 Templeton, Jan 14, 2025 at 3:47 PM
    Last edited: Jan 14, 2025 at 7:10 PM
  13. bisco

    bisco cookie crumbler

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    About a gallon based on miles driven and mpg, iirc.
    Made it to a gas station, but running out in the middle of nowhere is not something I’ll risk again
     
    #33 bisco, Jan 14, 2025 at 6:05 PM
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