Month of April 2020 (Nat’l Avg $1.984)

Discussion in 'The Daily Grind' started by EdwinTheMagnificent, Apr 1, 2020.

  1. RedylC94

    RedylC94 Well-Known Member

    The best way, and assuming the display error is actually a constant, is this:
    Over several consecutive fills, record the volume the display claims you burned, and the volume the pump says each time. Add them up and divide claimed total gallons by pump total. This will give the true error factor, unlike figuring the error factor for each fill and then averaging those numbers. This works even if there are partial fills in the middle, as long as the starting and ending fills-ups are reasonably complete and consistent.

    By the above method, my error factor has been very consistent ever since I got the car.

    Apologies, and never mind, if you're already doing this.
     
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  2. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Yeah , I like to assume that the Yota fcd error is a constant , lol. And I also want to
    believe that the pump clicks off consistently each time.

    Thanks , that was very helpful. I will try to calculate this based on these two tanks , and
    again with three tanks the next time I fill about ten days from now.
     
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  3. litesong

    litesong litesong

    Your use of 0.945 to gain a more accurate MPG figure, may be related to my use of 87 octane, ethanol-free gasoline (E0) & comparison of MPG to 87 octane 10% ethanol blend (E10). My five 87 octane gasoline engines, comparing 87 octane gasoline E0, to 87 ethanol blend E10, gave 8%, 8%, 7%-8%, 7% & 5% better MPG, paper & pencil. Often I reported that my cars' computer readouts tended to be more accurate using 87 octane E0, than 87 octane ethanol-blend E10. I believe it not coincidental that your quantity, when inverted is (1/0.945)= 1.0582. The factor 5.82% is located between my 8%, 8%, 7%-8%, 7%, & 5% calculations.
     
    Last edited: Apr 24, 2020
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  4. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Today , 43 deg F in Naperville , 41 in Elk Grove.
    Wind is NNE 9 MPH.
    35.1 miles , fcd = 59.9 x .943 = 56.5 MPG.
    Tank is at 110.2 miles , fcd =64.8 x .943 = 61.1 MPG.
     
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  5. litesong

    litesong litesong

    I see that you have changed your previous (0.945) to (0.943). As I have done previously, taking the inverse in my previous post, ( 1/0.943) becomes ( 1.06044). The factor 6.044% is even more cozily tucked in, with my five car comparisons, 87 octane E0 vs. 87 octane 10% ethanol blend E10 of 8%, 8%, 7%-8%, 7%, & 5% extra MPG.
    For years, it has been my contention (mostly poo-poohed by E10 advocates) that the burning of 87 octane E0 gives more accurate MPG readings on auto MPG computer readouts than MPG computer readouts while using (not burning efficiently) 87 octane 10% ethanol-blend E10. In essence, EdwinTheMagnificent, your factor (either 0.945 or 0.943) from experience just to adjust the auto MPG readouts to deal with the auto MPG inaccuracies, is halfway to confirming my understanding. The other part of research (if you would ever like to pursue such) is to use 87 octane E0 on a long-term basis, to see if burning 87 octane DOES INDEED, accurize your auto computer MPG readouts. I believe such would be the case, even tho I was always more interested in the MPG differences between fuels, than accuracies or inaccuracies of auto computer readouts.
     
    Last edited: Apr 24, 2020
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  6. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    0.943 was just a wild-ass guess. Will calculate when I get three tanks from that pump.

    Finding E0 for just ONE tank is too difficult to attempt. I will keep using E10.

    Actually , I'm not that magnificent. Just Edwin is fine.

    My "original" fcd error was 6.5-7.0 %. If it comes out to 5.7% (0.943) , I am okay with that
    .
    My Scanguage died a long time ago.
     
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  7. RedylC94

    RedylC94 Well-Known Member

    My fudge factor is consistently about 0.956. I don't know whether E0 would "accurize" it, because I haven't seen the stuff priced attractively, especially since it's typically found only at ratty-looking non-Top Tier convenience stores. Some folks say nominal E10 sometimes actually contains significantly under 10% ethyl alcohol, now that real petroleum is so cheap. If so, that inconsistency doesn't seem to affect my fudge factor much.

    My Scangauge works as well as ever, which is not perfectly, because it can't cope with fuel cut-off during coasting, therefore can not be calibrated for any variable related to measuring fuel consumption. Also, the traction battery current readout bounces around erratically; I assume it averages about right. Otherwise, it's fine.
     
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  8. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    Too many factors for me to worry about, especially when I add in variable battery charging from non-gasoline and non-regenerative braking sources. Another wild card is the fuel density at a given temperature, odometer errors, variations due to tire size over time as well as rotational differences going around corners/curves, etc. I just look at the significant 2 to 3 digits on the aFCD and if I'm doing better than the day before, then I'm happy, and if that's significantly off, then I'll wonder why and look into the cause if I cannot explain it away based on driving conditions. A 3-7 percent mental adjustment of the aFCD on Prius seems good enough. I don't worry about e10 vs e0. I'm with Edwin and others. Hard to find near me and not worth searching or driving farther for it.

    My SG II is still functioning and still saps the 12V battery on the Prius Prime (and not surprisingly on the Crosstrek Hybrid as well) if I don't unplug it.
     
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  9. RedylC94

    RedylC94 Well-Known Member

    Changes in the odometer error have zero effect on the percentage programmed-in overestimate of mpg (i.e., underestimate of fuel consumed). If replacing the tires results in a change in odometer error, then both the real and indicated mpg will change by exactly the same proportion. Odometer accuracy doesn't vary with wear of radial tires as much as people imagine.

    Aren't modern fuel pumps designed to compensate for temperature?
     
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  10. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    I don't know on any of these possible error sources. But I must be missing the reason why distance measurement errors won't affect the mpg calculation, but unless you're thinking the variation would track between aFCD and hand calculations at fuel up. I would agree on that tracking, but both would be equally inaccurate. I'm basically saying accuracy is a delusion.
     
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  11. Gord

    Gord Super Moderator Staff Member

    Been AWOL ;)

    Tuesday night going home on the bike, 45°F, mostly headwind ENE14 gusting to 26:
    No fuel / 20.1 / avg 14.9mph - slow

    Wednesday morning, motorway route, 42°F, tail/crosswind NE12:
    50.5 / 21.4

    Weds night, motorway route, 61°F, head/crosswind NE12:
    47.5 / 21.3

    Thursday morning, motorway route, 42°F, cross/tailwind NNE9:
    50.5 / 21.4

    Thu night, motorway route , 64°F, head/crosswind ENE9:
    48.1 / 21.3

    Back into work on different lighter bike Friday morning (Specialized Tarmac), 41°F, crosswind N4:
    No fuel / 19.9 / avg 17.3mph

    Back home, 60°F, headwind 5E:
    No fuel / 19.9 / avg 17.0mph

    Tank down 0.4 to 49.5 (FCD 52.1) / 261.2 / Range 430 . Guess gauge F__««|««««E . UG down 0.1 to 53.0 / DTE 454

    Lost pip 2 (of 8) @ 245 miles
     
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  12. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Today , 44 deg F in Naperville , 43 in Elk Grove.
    Wind NNE 7.
    35.1 miles , fcd = 61.2 x .943 = 57.7 MPG
    Tank is at 177.6 miles , fcd = 65.8 x .943 = 62.0 MPG.
    If this wind stays the same , it would help a lot on the way home.
    But it won't..... because you know , Chicago.
    But it might , too.
     
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  13. litesong

    litesong litesong

    Many decades ago in Spring time, I took a trip to NYC. I worried about the Cascade mountain travel, wondering if I would get some snow. But it was wonderfully clear. I worried about Northern Rocky Mountain mountain travel, wondering if I would get some snow. But, it was wonderfully clear. I worried about High Plains travel(8000-9000feet), wondering if I would get some snow. But, it was wonderfully clear. Later, I worried about Southern Rocky Mountain travel, wondering if I would get snow. But, it was wonderfully clear. I didn't worry about Lake affects snow around Chicago. That is where I got snow.
     
    Last edited: Apr 26, 2020
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  14. RedylC94

    RedylC94 Well-Known Member

    Of course errors in distance measurement will indeed affect mpg "hand-calculated" from it. I was only trying to point out that such distance errors will affect displayed and "hand-calculated" mpg equally, and therefore the correction factor to obtain actual fuel consumed from displayed fuel consumed (= displayed miles divided by displayed average mpg) is unaffected. (The correction factor to obtain actual mpg from displayed mpg would then be the inverse.)
     
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  15. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Today , 37 deg F in Woodridge , 38 in Elk Grove. Wind SSE 2.
    23.3 miles , ave speed 27 , fcd = 74.1 x .943 = 69.9 MPG.
    Tank is at 245.8 miles , fcd = 66.8 x .943 = 63.0 MPG.
     
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  16. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    Really great results!
     
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  17. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Thanks , Bill. Right now the wind is SSW 21 MPH , which means
    "brutal headwind all the way home". At least it's not raining. Yet.
     
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  18. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Going home today , 60 deg F , wind SSW 16.
    I beat the rain. Yes, glides were shorter.
    32.1 miles, fcd = 71.5 x .943 = 67.4 MPG.
    Tank is at 278.0 miles , fcd = 67.4 x .943 = 63.6 MPG.
     
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  19. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Today , 55 deg F in Naperville , 48 in Elk Grove. These numbers are from wunderground today ;
    weather.com was broken. No wind at all , but increasingly foggy in the second half of my trip.
    35.1 miles , fcd = 66.0 x .943 = 62.2 MPG.
    Tank is at 313.2 miles , fcd = 67.2 x .943 = 63.4 MPG.
     
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  20. Gord

    Gord Super Moderator Staff Member

    Yesterday morning to work on the bike:
    No gas / 20.0 / avg 15.2mph

    Last night going home on the bike, 55°F, headwind E6:
    No gas / 19.5 / avg 16.2mph

    To work in the car this morning - had to park on a street as usual work car park was unavailable, motorway route, 45°F, cross/tailwind NE7:
    51.8 / 21.1 (FCD was 54.6)

    I’m using a .9497 correction factor as my average FCD over-read is 1.053% over 64 tanks.

    Tank up 0.2 to 49.7 (FCD 52.4) / 282.3 / Range 400 . Guess gauge F__««|««««E . UG up 0.3 to 53.3 / DTE 437
     
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