Pure Gas ( No Ethanol ) experiment

Discussion in 'Prime Main Forum (2017-Current)' started by Blue-Adept, Apr 28, 2019.

  1. Blue-Adept

    Blue-Adept Member

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    Final Results. Costco regular gas cost today $2.69 a Gallon in Michigan. Pure gas. $4.00 a gallon.
    - The car feels smother to me in HV
    - Don't see how I can figure out real fuel mpg.
    - Not worth cost if you burn a tank a month as I do.
    - Worth it if you fill up every few months or years.

    I will still use pure gas for my power equiptment.
     
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  2. Zed Ruhlen

    Zed Ruhlen Junior Member

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    As for evidence, actually I DO have evidence. My personal cars. They have test sections on major freeways. I have done the math on almost every car I have owned and not a single one is accurate. Our Sienna is off by 5% (and it shows up in my navigation as the speed being off). I haven't tested the Prius because I haven't driven past one of the test sections.

    As for DTE having 1.9 gallons in the tank I imagine this is different on every individual car. Mileage estimates are notoriously inaccurate but why bother at all if you have another 100 miles?

    As for the fuel pump, well gosh, one person did a test and didn't have a fuel pump failure. I guess that negates the whole issue. Sorry for the sarcasm but it is well known that you should never run your tank to empty.

    The pickup isn't in the very bottom of the tank which is why there will be fuel in an "empty" tank. Car talk did a puzzler about this once. You run out of gas and have a couple of miles to get to your wedding. In the car you have: a quart of olive oil, a quart of water, and a quart of engine oil. What do you put in the tank to get to the wedding? Answer is water. The remaining gas will float on the water allowing the fuel pickup to get gas but NOT the water since gas floats.
     
  3. fuzzy1

    fuzzy1 Senior Member

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    I was referring to odometer, not speedometer. They don't have the same display errors, so don't confuse them.

    How much does your GPS navigation distance (not speed) differ from your car's trip odometer (not speedometer)? Please don't stop at just 5 miles, continue out to 20+ or even 100 miles.

    I have tested all my modern car's odometers against long runs of surveyed mileposts (which are sometimes infested with 'busted' sections that need to be weeded out). My '14 Forester, post-lawsuit, reads 1.8% low. '12 Prius reads about 0.2% low. A pre-lawsuit Subaru, Honda, and Toyota were all within 0.5%.

    A few tests with GPS trip meters turned up nearly identical results, but only after turning off the battery-saver mode and getting out of the deep valleys. Those factors had been causing the GPSs to jump around and read high.
    The very best post for this in all of PriusChat, for Gen3, is the first post of this very long thread:
    [WARNING] Running out of gas (Gen III)

    There are vastly more than just one person in PriusChat who have run their tanks low. So if this is really as serious an issue as you portrayed, there should be many first-person examples and problem reports here.

    So where are they? Crickets ...
     
    #143 fuzzy1, May 19, 2019
    Last edited: May 19, 2019
  4. Trollbait

    Trollbait It's a D&D thing

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    The E10 cost you 6.25 cents a mile, and the E0 was 7.06 cents. Less than $9 for 1000 miles, if the ethanol content was the sole cause for the difference.

    Can the car display HV mode only MPG, or is all mixed in with EV miles? Perhaps go without charging for a hundred miles without charging after a fill up.

    The displayed MPG may not be the true consumption, but however how much it is off by should be close to constant for our use here.
     
  5. jb in NE

    jb in NE Senior Member

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    I think it's designed for up to E15.
     
  6. fuzzy1

    fuzzy1 Senior Member

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    If your Sienna odometer (not speedometer) is off by 5% in the high direction, then there may be legal firms standing by to file class action lawsuits for warranty fraud. Long ago I received the legal notices for a Honda and a Subaru, and both companies settled for slight warranty extensions, which I didn't need. Other companies may have also been sued, but I didn't have their cars.

    Note that this is very specific to the odometer only, not to the speedometer.
     
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  7. bruceha_2000

    bruceha_2000 Senior Member

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    Yep. And diesel is usually 30 to 50 cents higher than E10 so even an efficient diesel car is no money saver over a Prius of any generation.

    Like how long? And can't she go into the store to hang out instead of sitting outside wasting gas? I ASSUME she has to go into the store to get the order anyway.

    BUT ... you have to use the SAME pump and in similar temperatures.

    I've completely run out 3 times in Gen IIs (never on purpose!) , no harm no foul. Lucky for me I was able to EV to a very nearby gas station two of those times. Had to wait on the interstate for the AAA gas can once. DD ran her 2010 out, had to wait for the Dad gas can.

    How much of the minimal difference (the .5%) can be attributed to tires wearing or the wrong size tires (like 195s instead of 185s on a Gen II non touring)?

    I think there is no way to separate the blended miles into MPG on gas/HV and MPG on EV alone.
     
  8. Trollbait

    Trollbait It's a D&D thing

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    Check the manual. The EPA required cars to be E15 compatiable by this time, but manufacturers and models started complying at different rates.
     
  9. jb in NE

    jb in NE Senior Member

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    191F3C36-8F4B-45CF-A356-CD1CA322926D.jpeg
     

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  10. fuzzy1

    fuzzy1 Senior Member

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    I've run out unintentionally just once, as a teen on the very first tank of a new-to-me car with the gas gauge still a bit above 'E'. This was not long after both parents teased me endlessly about being fearful of driving one of their cars with the needle right at 'E'. Mom even went a whole 'nuther week without refueling it, just to rub it in.

    All my subsequent cars have had at least 100-ish miles remaining beyond 'E' or the first low fuel warning. One car even had 1/3rd of its useable range down past that first warning, and I sometimes needed that range to get beyond 'convenience' 'tourist-trap' gas price gouging to reach the price-competitive stations beyond. I have intentionally run two cars out of fuel for tests, but not this Prius.

    As for the 'no harm, no foul' angle, there have been some harms reported here over the years. For the Gen2, mostly (before my PC time) traction battery problems from driving too far on EV-only mode after gasoline depletion. For Gen3 (I joined as this generation was being revealed), mostly ignition lockouts from too many start attempts without adding any, or sufficient, fuel. The first few required tows to shops for ECU resets, then others discovered that disconnecting the 12V battery long enough to erase volatile memory will also remove the lockout. But like you, most seem to have suffered no harms, just inconvenience.

    But the supposed harms put forth by ZD and numerous others for merely running down to DTE=0 (nowhere near actually empty), remain elusive here. And I am quite certain that the absence of reports, is not for lack of people going there.
    For me, none of it can be attributed to wrong tire sizes.

    As for tread wear, I haven't seen any definitive determination of exactly how much the tire rolling circumference changes with wear, only that it is 'approximately' zero. By that, I mean the change is far less than one would expect from applying the tread depth loss to the simple circle equations. This is consistent with other indications from tire specifications (readily available from TireRack.com) that their rolling circumference, computed from listed RPM (revolutions per mile), is consistently much less than expected from raw diameter. In fact, for the ones I've checked, it is even a bit less than the remaining diameter after the entire spec'ed tread depth is shaved off.

    Other indicators are that the tire's rolling circumference is set mostly by the length of the steel belts just beneath the tread. These change very little with age, tread wear, and inflation pressure.
     
    #150 fuzzy1, May 19, 2019
    Last edited: May 19, 2019
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  11. cnc97

    cnc97 Senior Member

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    I, repeatedly and often, run my tanks in all my cars, well past the 0 miles to empty indicated. Simply because it never seems to line up on a convenient time. Sometimes I go 20 miles, sometimes 50. In the case of my Gen 3, I went 125 miles. The closest I have ever come to total tank capacity at refill was in the Prius, at adding 11.808 gallon. My Explorer goes to 0 miles to empty at 18+ or - gallons, with a tank capacity of 22 gallons. And the wife’s Edge hits 0 at 15 gallons, with a tank capacity of 18. My Prius has 223k on the original fuel pump, the Explorer is at 216k, with a pump change at 190k due to the sending unit quitting. The Edge just hit 102k, so I don’t foresee any harm coming to it soon.

    Just my $.02 on potential harm from doing so.
     
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  12. jb in NE

    jb in NE Senior Member

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    I've been doing this fairly frequently on my new Prime trying to get a feel for how much reserve there is at indicated empty. Last week coming back from Canada, the car was reminding at me to put in gas. Zero miles to empty, etc. I put in 10.435 gals at the 551 mile point (filled to the brim) on an 11.4-ish gallon tank. Plenty of reserve, that's at least 50 miles. The week before, I put in 10.713 gals at the 648 mile point, also past zero miles to empty.
     
  13. George W

    George W Active Member

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    The amount of time was mentioned earlier in this thread. Since you insist on assuming that a shopper can just loiter in a grocery store indefinitely, you clearly don't have a clue of the rules a Delivery Service must respect.


    I don't care what it cost over 1,000 miles, just what it cost over 3 tank fills. an extra 25 miles is not worth the extra $5 spent to achieve that. The driving habits are the same, the hours of idling with the A/C would be the biggest difference, some days are busier than others.
     
    #153 George W, May 19, 2019
    Last edited by a moderator: May 22, 2019
  14. Zed Ruhlen

    Zed Ruhlen Junior Member

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    As I said, I use DISTANCE signs on the highway. So the ODOMETER is inaccurate. And since the Odometer and SPEEDOMETER typically use the same sending unit (or cable in an older car) they are often inaccurate at the same rate.
     
  15. Zed Ruhlen

    Zed Ruhlen Junior Member

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    No. Mythbusters destroyed this myth long ago. Gas pumps are calibrated to a high degree of accuracy and the temperature has almost zero effect. For a variety of reasons: the amount is so small that temperature changes don't really affect the volume much and the consistency of the temperature of the gas because it is stored underground where the temperature is pretty stable.
     
  16. fuzzy1

    fuzzy1 Senior Member

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    Are you using the specially calibrated check sections, or random mileposts? I've found a number of mileposts offset for mounting convenience, and some sections 'busted' by subsequent realignments that shorten the road. Some of the later are well marked, some are not.

    So when using mileposts, short stretches are no good, I must use long stretches. And by noting readings at many different mileposts, I can usually locate the offset posts and survey 'busts'.

    Is your odometer reading high or low? If high, and it is a pattern of your model instead of an individual problem, then there are product liability legal firms ready to go after the maker. They already shaken down some brands. Because of that, my current Subaru odometer reads significantly low to avoid future tort claims.

    The 'same rate' part is simply false for most vehicles. For industry standards and legal reasons that have been discussed repeatedly over the years here, speedometer must not read low, while odometer must not read high. This is normally addressed by making speedometers intentionally read high. And high by different amounts in different markets (U.S. vs Europe vs. other portions of world).

    On the Prius, this speed offset is built into the display only. The internal computers know the speed quite accurately, and you can even see this measure with an OBDII-port monitor.

    ===================

    Do you have any more comments about the supposed mechanical dangers of running fuel down to DTE=0?
     
    #156 fuzzy1, May 21, 2019
    Last edited: May 21, 2019
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  17. Zed Ruhlen

    Zed Ruhlen Junior Member

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    yes
     
  18. Salamander_King

    Salamander_King Senior Member

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    Huh??? Have you checked this on your PRIME??? My Prime's odometer is dead on accurate. Comparing to mile marks on an interstate or using GPS, it has less than a mile of difference in >300 miles I have checked. The speedometer, on the other hand, is known to be off by a few miles at highway speed.
     
    #158 Salamander_King, May 21, 2019
    Last edited: May 21, 2019
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  19. fuzzy1

    fuzzy1 Senior Member

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    And? ....

    (also, is it wearing the correct OEM tire size?)
     
  20. jb in NE

    jb in NE Senior Member

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    How many signs are you using? Since the car only displays the odometer in 1/10 mile increments, even if you use the calibrated distance markers on the highway you need to use at least 10 miles of them to get to the displayed level of accuracy. If your odometer is still reading 0.9 miles when you get to the first one, it could be anywhere from 0.9 to 0.99 miles elapsed on the odometer. If you go the full 10 miles, you lower that error by a factor of 10. Now it's between 9.9 and 9.99 miles over 10 miles. The longer the measurement interval, the less the error in the calculation.
     
    #160 jb in NE, May 21, 2019
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