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What is your DTE after fill-up? (Gen 5)

Discussion in 'Gen 5 Prius Fuel Economy & Prime EV Range' started by Gokhan, Aug 23, 2023.

  1. Gokhan

    Gokhan Senior Member

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    We had this thread in the Gen 4 Prius Prime forum. Distance-to-empty (DTE) miles seem to be calculated based on the recent tanks, and it excludes any BEV miles, which an owner cannot do when calculates mpg. It is not clear how many gallons are assumed to be in the full tank. It is not the tank capacity (11.4 gallons for Gen 4 Prius/Prius Prime and Gen 5 non-AWD Prius, 10.6 gallons for Gen 5 AWD Prius and Prius Prime), but at least a gallon or perhaps a gallon and a half or so less. You can estimate that by filling up when the DTE becomes 0.

    Users recorded greatly varying DTE values for Gen 4 Prius Prime, ranging from 400s to 700s, depending on driving styles. The record—achieved by me—was 768 miles.

    Note that DTE will be less for Gen 5 Prius AWD and Gen 5 Prius Prime due to reduced tank capacity (10.6 gallons vs. 11.4 gallons).

    Let's see your DTE values at fill-up!

    (Note: To get the DTE at fill-up, toggle to the DTE reading and bring the car to READY mode and then wait for several seconds or drive a few yards.)

    What is your DTE after fill-up? | PriusChat
     
  2. Preebee

    Preebee Senior Member

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    DTE is not real-time accurate. Not even close. It's a lagging indicator at best. It's calculations are based on tank capacity minus 2 gallons. If your driving style differs between tank to tank it will be wildly off.

    The gold standard is still miles driven/fuel replaced.

    Tank average is a better real-time indicator. My last tank was only .5 MPGs (manually calculated) from what my tank average meter stated (62.xx MPGs).
     
  3. Gokhan

    Gokhan Senior Member

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    If you think so, report your total average, not tank average. We don't know if you're cherry-picking your tank averages. DTE is a long-time average.
     
  4. tovli

    tovli 2023 Prius Prime replaced 09 Prius

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    I'm not sure this is always correct. My last DTE was 474 miles with a 10.6 gallon tank. If I subtract 2 gallons, it would suggest the car is computing DTE based on 55 MPG which is way off what I have measured (miles/gallons added).

    My miles/gallons added average is 44.7 MPG and the DTE / TotalTank (474 / 10.6) is also 44.7 MPG suggesting the DTE is using the entire tank (in the Prime XSE case). The car's indicated "Tank Average" remains stuck at 99.9 MPG though since that computation uses total miles driven not just HV miles.

    I beg to differ - individual fill ups vary causing individual MPG values to vary quite a bit. My "minimum standard" is average over at least three fill ups.
     
    #4 tovli, Aug 24, 2023
    Last edited: Aug 24, 2023
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  5. Gokhan

    Gokhan Senior Member

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    I think it is more like one gallon remaining in tank. You can find out exactly how much by toggling to DTE with low fuel and then switch to the BEV mode and fill up as soon as DTE becomes zero.
     
  6. Preebee

    Preebee Senior Member

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    With respect to 2023 LE's (11.3 gal capacity)...I refueled at 0 DTE. I had driven 600 miles, and put 9.7 gals in, at the same pump, using the exact same methodology as last time. Accuracy would be within a couple ounces (128 oz/gal).

    That equals 1.6 gals left after DTE=0.
     
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  7. Preebee

    Preebee Senior Member

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    Agree to disagree then. :)

    Same station, same pump, lowest auto-setting, no top-off = rounding error.
     
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  8. HacksawMark

    HacksawMark Active Member

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    Agree with both. Miles driven vs fuel replaced is the only real way to calculate true MPG. The more fill ups tracked, the more accurate the measurement will be.
     
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  9. Gokhan

    Gokhan Senior Member

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    It sounds good. It is actually 11.36 gallons (43 liters). So, the remaining fuel would be more like 1.7 gallons.

    In that case, I expect your DTE to be around 600 miles, which is above the average for a typical Prius driver. Your tank average is 62 mpg. As I said, I was able to reach a DTE record of 768 miles with my blue 2021 Prius Limited, which would then correspond to a tank average of 79 mpg. However, I was hardcore hypermiling and my car probably overestimates it by 5 mpg; so, it was probably a true fuel economy of 74 mpg.

    The last DTE I got was 712 miles, with not as much hypermiling, which would correspond to about 73 mpg or 68 mpg after accounting for the 5-mpg overestimation. These consistent ~ 70-mpg tank averages I have been getting are a lot of mpg! :)
     
  10. Preebee

    Preebee Senior Member

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    My avg. tank reading was .5 MPG's from my manually calculated fuel economy. One was slightly over 62 MPG's, the other slightly under.

    I was just a bit over 65 MPGs before I parked my car for 2.5 hrs and used it as an air- conditioned dog kennel on a very warm day.

    We are in the middle of one of the worst heat waves in modern history. I've been driving in temps that have reached 110F. The AC is on all the time.

    My G4 would have been clocking mid-50's if I was lucky. It was particularly susceptible to heat and AC MPG penalty.

    When the weather cools, and I can drive without AC, I'll hit 70 MPGs on a tank easy. And I'm accelerating with the traffic. No exotic maneuvers necessary. The G5 just glides on battery for days...
     
  11. Gokhan

    Gokhan Senior Member

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    Well, heat increases the mpg by lowering the air drag (it makes the air thinner). Especially in hot, dry air your mpg will be a lot higher than in cold, damp air.

    Gen 5 seems to be somewhat less aerodynamic than Gen 4. I think Gen 4 Prius Prime was even more aerodynamic.

    2023 Toyota Prius punches it up

    So, I find it hard to believe that you would get consistently 13% higher mpg than with your Gen 4.
     
  12. Mr.Vanvandenburg

    Mr.Vanvandenburg Senior Member

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    Why do you think your precisely measuring car would read less fuel used than was? I just don’t understand the theory behind that belief. Fuel is measured accurately in very tiny amounts into the cylinders. Suddenly they decide somewhere to fudge the numbers? I would much more disbelieve gas pumping and all that entails. It’s not easy to discuss because people get in a camp and stay there. Maybe I’m in a camp, but at least I am open to I could be.
     
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  13. Gokhan

    Gokhan Senior Member

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    I will go through my gas receipts to see what makes sense. It is hard with the Prius Prime to separate the BEV driving.
     
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  14. Gokhan

    Gokhan Senior Member

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    So, I did a quick-and-dirty estimate of my BEV miles in my last tank—847 miles between gasoline fills, 9.372 gallons, assumed about 35 BEV miles a week, which is slightly less than one full charge of about 38 miles, six weeks between the fill-ups, which then gives 210 BEV miles—and I came up with 68 mpg, which agrees with the number I calculated from my last DTE after subtracting the 5-mpg overestimation.

    I think the Gen 4 Prius Prime display automatically adds 5 mpg to every real mpg value. Why did Toyota did this? I don't know.

    Incidentally, the speedometer automatically adds 2 mph to every real mph value. This is understandable from a safety and legal perspective.
     
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  15. tovli

    tovli 2023 Prius Prime replaced 09 Prius

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    Really? My 2023 Prius Prime XSE is spot on with the GPS speed of WAZE (and the stupid "Your Speed Is" sign I went by twice yesterday)
     
  16. Mr.Vanvandenburg

    Mr.Vanvandenburg Senior Member

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    I used to watch for a mile marker , then try to go exactly sixty while looking at my watch second hand as the next mile marker went by. So it should be one minute.
    What if a person set a trip to zero, went sixty, and timed it?
     
  17. Gokhan

    Gokhan Senior Member

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    I use GPS speedometer apps.
     
  18. Gokhan

    Gokhan Senior Member

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    It will vary with the tire revolutions per mile spec etc. However, the difference is constant regardless of speed; so, it seems to be an intentional 2-MPH difference by Toyota.
     
  19. tovli

    tovli 2023 Prius Prime replaced 09 Prius

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    Are you serious or joking? I'm not very good at detecting sarcasm.
     
  20. Mr.Vanvandenburg

    Mr.Vanvandenburg Senior Member

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    Are you sure it’s intentional by Toyota to deceive us? Maybe it’s unintentional. Which app is free you use? So this is better than my holding steady 60 and clock, odometer method? I want to try the app and see for myself.
    One thing my old method is better for brain exercise than gps.