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After fill-up, estimated mileage range 100 miles less than original

Discussion in 'Prime Fuel Economy & EV Range' started by DeeHaa, Apr 2, 2020.

  1. DeeHaa

    DeeHaa Junior Member

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    Howdy all,

    I have a question about Prius Prime 2017 mileage. When I bought my car in 2017, every time i top off my tank (without electric), start driving and the estimated mileage on panel was 525 miles range. After 3 years of driving, i notice that every time I top off my tank (without electric), start driving and the estimated mileage on panel is 425 miles range. it reduces 100 miles per tank. Where is 100 miles or why is that ? Does anyone know why ? My car has not tune up yet, no warning not symptom of any engine trouble. Engine is running good. Change Mobil One 5/20 oil every 10K. Change air filter every 12K. New 4 tires. My car mileage is 90K.

    thanks so much,

    DH.
     
  2. bisco

    bisco cookie crumbler

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    not much value in that metric. have you ever driven from full to empty to see how many miles you get?

    do you keep track of mpg's when you fill up?

    do you use a trip meter to track mpg's?
     
  3. jerrymildred

    jerrymildred Senior Member

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    Bisco's questions might get you on the right track. The DTE is based on previous performance. If it's fallen, then that seems to indicate that your gas mileages has fallen recently. In fact, one of our members (@Salamander_King) has expressed his opinion that DTE at fill up a good indicator of how you did on the last tank. As Bisco said, though, the DTE number is not the main thing. The only number that really matters is the result of dividing the miles driven on a tank by the amount of gas used. Unfortunately, that's a virtually impossible number to find on a Prime. Perhaps you might try starting with a full tank and driving for maybe a half tank in only HV mode and then full up again and calculate the mileage.
     
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  4. Salamander_King

    Salamander_King Senior Member

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    Yap, as others commented DTE is just an estimate of full tank distance using only HV mode based on past performance. I am not sure if it is strictly on the last tank only, but most likely only for very recent HV drives. Look at this thread. What is your DTE after fill-up? | PriusChat My 2017 PRIME's DTE ranged from 574 miles in the summertime to 450 miles in wintertime. The difference is roughly what I expect from the seasonal differences in HV only mpg.

    summer mpg 61.6 (573÷ 9.3)
    winter mpg 48.4 (450÷ 9.3)

    where 9.3 is the gallon of gas used from fill up to empty light comes on (2 gal less than the tank capacity).
     
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  5. DeeHaa

    DeeHaa Junior Member

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    Thanks all for the thought.
    The way i calculate my Prime is i top off my Prime, reset Odometer A. Drive until it lest than 40 miles of DTE, then top off again. this time i jot down the number of gallons filled up and divide by number of mileage drove (using Odometer A). it is about 40 miles per gallon. Did it many times (everytime top off)
    Start to drive, get number of DTE about 425 miles. Note that my car has no load, no passengers, just my weight as the load.
     
  6. bisco

    bisco cookie crumbler

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    40 mpg is pretty bad, unless you're racing
     
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  7. Salamander_King

    Salamander_King Senior Member

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    Do you charge your car? Driving EV will inflate the mpg since you are not using gas but the car is recoding the miles. In any case, your 40 miles per gallon is very low for PRIME. What type of driving conditions? Speed, distance/trip, use of the heater, ambient temperature, any hill climbing?
     
  8. jerrymildred

    jerrymildred Senior Member

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    Our 6,000 mile trip last May gave me quite a bit of highway HV driving data. My worst tank ever in a Prime was last May. Driving east across Iowa into 50 mph headwinds. The wind slowed everyone down to about 50 mph. On that tank I got 42.02 mpg. :mad: A few days before, while touring Colorado, I got 61.57 followed by 65.55 mpg. :cool:

    It's hard to imagine only getting 40 mpg in a Prime. Something is really wrong , which I guess is what initiated your original post.

    Given that it didn't use to be this bad according to the change in DTE, something has changed.

    It could be dragging brakes. Filters. Tires. New tires cause a hit to mpg and especially if they are not low rolling resistance tires or the wrong size. The heavier than spec oil is causing some drag, but that can't be the whole problem. How about the panels under the car. Any damage there bad enough to increase drag?

    I'm just guessing. It sounds like it will need a good going over to sort out what's different unless you know of something you might have changed to cause it. The tires are capable of making a big difference if they are the wrong ones.
     
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  9. DeeHaa

    DeeHaa Junior Member

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    My 2017 Prime has 2 issues here:
    a. Why my DTE after top off tank is ~425 (without any driving yet, compare with 3 years ago was ~525). No warnings, errors on panel.
    b. If actually calculate the mpg, it is about~40 mpg. I subtract the # miles if i charge during the time of using the tank.
    i use cruise control most the time when driving from the beginning, so wont make any different here.

    The recently changes last year are two things:
    1. i used 0-20 Mobil One but for 150K which much thicker, 2 months ago i changed back to normal 0-20 Mobil One.
    2. New 4 tires. The new tires is the same size but with different brand name. The original ones were Dunlop 195/65/15, new ones are Bridgestone 195/65/15 91H installed by Costco.

    Only think i agree with Jerry : I have to exam underneath the car to see any damage by hydraulic it up in the shop. By looking with my naked eyes, i don't see any damages.

    Nowadays, car has computer with error codes, it will display if it detect something abnormal. Mine has none.
     
  10. Salamander_King

    Salamander_King Senior Member

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    If you are really getting 40mpg then it explains why you are getting 425 miles on DTE after a fill-up. The car is using the last tank mpg for the estimation of the DTE. 425 miles is about 45.7mpg (425 ÷ 9.3), is it still higher than your calculated mpg, but close.

    New tires will lower your mpg, but by itself, 40mpg is too low. If you were using 5W-20 oil, that also lowers mpg. Have you had cold weather? You may have had combinations of mpg lowering factors together, but yeah, I would check what @jerrymildred suggested. Brakes and undercover for sure.
     
    #10 Salamander_King, Apr 5, 2020
    Last edited: Apr 5, 2020
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  11. bisco

    bisco cookie crumbler

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    did you ever check your mpg at the pump when you dte was 525?
     
  12. FuelMiser

    FuelMiser Senior Member

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    1) Look on top of your Oil Fill Cap under the hood: it should say "0W20" 5W20 is not that different, but no reason not to use the recommended. 2) "New 4 tires" will always change the MPG immediately! Especially if you don't the buy the fuel efficient, low rolling resistance type. Also, tires vary in weight. Maybe you bought heavier tires. Maybe the tire shop did not inflate to the most efficient pressure. Bottom Line: whenever the car changes behavior suddenly, always look at the last maintenance item you did on the car--change tires? Check your tire pressures.
     
  13. fotomoto

    fotomoto Senior Member

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    Are these non-stop miles; highway or urban, etc?
     
  14. Mendel Leisk

    Mendel Leisk Senior Member

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    Can you more specific regarding the Bridgestones? Post the full name of the tire.
     
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  15. DeeHaa

    DeeHaa Junior Member

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    Checked underneath the car, everything is fine. See nothing wrong underneath. I drive most on highway.
    The 4 new tires :
    Bridgestone Turanza Quite Track, All season touring, 195/65R/15 91H BW, 80K miles warranty
    I pretty sure the new tires tracks cause the reduce of mileages.

    They are inflated properly by Costco.

    Still no error display at all on dash panel.

    I plan to change spark plugs at 100K (soon)
     
    #15 DeeHaa, May 2, 2020
    Last edited: May 2, 2020
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  16. DeeHaa

    DeeHaa Junior Member

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    My typo. I never use oil 5W20, Just 0W20. One time I used 0W20 15,000 Miles but that oil is thick, so, I don't use it again.