Easy way to check gas mileage?

Discussion in 'General Motoring' started by houndman, Sep 10, 2007.

  1. houndman

    houndman Guest

    I have about 600miles on the Imp 2.5i 5M and haven't been babying it,
    though trying not to rev it too high yet. Started with a full tank and
    added some gas here and there and rough figuring it looks like 30mpg,
    which I doubt. Though I've put a good bit on on highways, I haven't
    driven for economy, and red lights and all 4 way stop streets in the
    city, and trying to figure out the best shift points should have made
    the mileage really low.

    I believe the cars have a low fuel light, so planing on running it
    down to light it, and then adding gas and runing it down again.
    Figured that would be an easy way to figure how much gas I used.

    houndman, Sep 10, 2007
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  2. You write the mileage on your gas ticket, reset the trip OD to zero
    throw the ticket in the glove box and every so often, put them in a
    spread sheet that has been set up with all the calculators. Then,
    over time, you have a good read.

    such as:

    Subaru Forester

    Tank no. miles gals mpg %highway highway miles
    city miles

    1 263 9.76 26.95 65% 171.0 92.1 AC
    2 276.1 11.036 25.02 63% 173.9 102.2 AC
    3 271.5 12.168 22.31 0% 0.0 271.5 AC
    4 280.7 12.199 23.01 0% 0.0 280.7 AC
    5 236.5 10.851 21.80 0% 0.0 236.5 AC
    6 222 9.486 23.40 64% 142.1 79.9 AC
    7 255.7 11.305 22.62 31% 79.3 176.4 AC
    8 530.7 24.486 21.67 0% 0.0 530.7 AC two

    2336.2 101.291 23.06 566.2 1770.0
    24% 76%

    Doesn't paste exactly lined up into the news reader, but you get the
    picture. BTW, not knocked over by the Forester mileage, particularly
    city miles. On the two tanks, missed a reset, no harm done just add
    the two tickets together.

    Frank Boettcher, Sep 10, 2007
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  3. houndman

    houndman Guest

    I usually don't fill the tank unless I am going to NJ from PA, where
    gas is .40-.50/gal. cheaper, And they pump it, so was looking for
    ideas to check smaller fills. Really just want a rough idea, since big
    city driving can really cut in to mileage, though the new Sube has be
    exploring again. Introducing it (and me again) to some neat roads.))

    houndman, Sep 10, 2007
  4. houndman

    David Guest

    Fill the tank (let the pump shut off automatically. Do not top off.)

    Reset Trip Counter to Zero.


    Fill tank again. Note # of gallons needed to fill tank.

    Divide Trip Counter reading by gallons needed to refill tank for your

    I keep a cheap solar powered calculator in the passenger cabin for
    this ritual.

    You can also get a meter that plugs into your OBD-II port and will
    give you a constant readout of running MPG.
    David, Sep 10, 2007

  5. With the methods suggested it doesn't matter how large the fill is.
    The only thing that needs to be constant is letting the pump self shut
    down each time and don't try to push any more in the tank.

    Frank Boettcher, Sep 10, 2007
  6. houndman

    Todd H. Guest

    Its not feasible I'm afraid. Without filling the tank, or
    establishing some means of knowing a given gas tank level, you have no
    fixed measure of how much gas was consumed in the miles driven.

    But I have an idea.

    If you are interested in knowing your mileage, plan a trip to PA where
    you can in good fiscal conscience fill your tank, then, when back in
    NJ, affix a small red E to the instrument cluster where the 3/4 of a
    tank line is on your fuel gauge, and pretend you're running out of

    This will get you the emotional comfort of smaller fills, and be able
    to fill the tank on every fill, so you can resetting the trip odometer
    and have a chance of calculating mileage. And you'll never run out
    of gas.

    Best Regards,
    Todd H., Sep 10, 2007
  7. houndman

    Frank Guest

    First mileage on my Forester was erratic but high. Found tires were
    inflated to 40 lb. which probably helped mileage. Others said this is
    common and dealer said they come like this out of factory but they did
    not adjust in car prep.

    Frank, Sep 10, 2007
  8. houndman

    Lyle Chase Guest

    David; Tell me more about the meter for MPG that's driven by the OBD-11
    Thank you, Lyle.
    Lyle Chase, Sep 10, 2007
  9. If the calculator is too cumbersome, you can get a little slide-rule
    sort of thing where you line up the miles and gallons, and it shows
    you the mileage. I got one as a freebie from my mechanic years ago
    that clipped onto the sun visor, and it was a great convenience for
    many years until it wore out. The nice thing was that you didn't have
    to write things down, since the slider would stay in whatever position
    you left it until the next time you gassed up (You still want to take
    notes if you're interested in more than a general "Did it get better
    or worse since the last time")
    L. Ross Raszewski, Sep 10, 2007
  10. houndman

    houndman Guest

    wouldn't the low fuel warning light come on at the same point? Read it
    won't go out unless you put 4 gal in. That eliminates my 5$ fill, or
    even 10$.(( Figure it wouild be pretty accurate, recording how many
    gal I put in and calc the miles till the light comes on again, and put
    more in asap, or add the miles since the light came on to the next #
    of miles, or is that subtract them??)

    houndman, Sep 10, 2007
  11. houndman

    Todd H. Guest

    I guess you could use that technique as a rather rough gauge (when it
    comes on does vary by incline IIRC). Would it give you two
    significant figures of precision in your mpg measurement? I dunno.
    When the tank's full and the nozzle shuts off, it's generally full
    with a rather low variation since the filler tube's diameter is such
    that you're not dealing with a lot of volume variation between
    different fuel nozzles, and the measurement ends up rather precise.
    With the low fuel light, you're dealing with a vertical fuel level
    measurement amplified over the area of a rather large tank.

    But really what's the point? Why not start filling the tank with more
    regularity? Averaged, I challenge you to prove that you're saving any
    money with these partial fills unless you're actively changing your
    destinations based on getting to PA for fill ups with cheaper gas on a
    regular basis (and in that case, is the savings nulled out by the fuel
    burned to get out there?)

    Best Regards,
    Todd H., Sep 10, 2007
  12. houndman

    Bugalugs Guest

    You also need to record the amount of fuel put in over at least 3 or 4
    fills. And it only needs to be 'full to the brim' at the start and on
    the last fill.

    Back a few years I competed in some 'economy' events and we found that
    some cars had a flat top to the tank and the breather was not at the
    highest point of the tank. As a result sometimes there was a bubble of
    air trapped in the top of the tank when it was filled at night.The
    competitor thought he had had a wonderful day. It evened out over the
    next few days. At the end of the event on the final fill we always made
    sure the cars were rocked from side to side to burp any trapped air out
    of the tank.

    Back then (mid 70s) we were getting 44MPG (Imperial gallon) out of a
    Bugalugs, Sep 10, 2007
  13. houndman

    houndman Guest

    I don't drive all that much, and putting in 30$ worth at one time
    seems like a lot of money, even 20$'s does.. It's NJ where the gas is
    cheaper, and I only go when I have to, and then I will fill up,
    because of the price.

    I was just trying to figure how to use some features the Sube has, to
    check mileage. After breaking the car in and learning all the
    controls, and adding all the parts I have bought to put on it, I may
    put very few miles on it, since I bought it as a more dependable ride
    to some distant places in a state forrest in NJ to go star gazing, and
    where relatives live.

    houndman, Sep 11, 2007
  14. Partial fills should be avoided. There was a time when that was the only
    way I could drive and my daughter has hit-and-miss funds and does
    partial fills. It is common, but really, it increases the amount of
    moisture and debris that enters the tank , and there is more evaporative
    loss, when the gas cap is off.

    Carl 1 Lucky Texan, Sep 11, 2007
  15. houndman

    Todd H. Guest

    But you realize this is all just mental. You're spending the money
    eventually anyway. You can go to the gas station just as often and
    put just as little gas in as you always do if you start looking at the
    3/4 full mark at the Empty line. And you'll be able to figure out
    mileage reliably.
    Todd H., Sep 11, 2007
  16. houndman

    houndman Guest

    I had an injury that damaged all systems. Brain damage and I had to do
    my Own cognitive therapy, because I couldn't handle the 5 day, 6hr/
    schedule, because I couldn't stay awake for more than 3 hrs. I would
    get So tired, I would hope I had enough gas to get to a station the
    next time I drove, because I coudln't stop on the way home, Getting
    home, even a few blocks, was pure agony. I had to relearn, math and
    spelling, because if short term memory damage, though long term was
    still in tact, so I would practice, and make up games and tests. Had
    to figure out the prices and add them up, Before i went shoping, so i
    didn't feel like I got overcharged. I couldn't do it on the fly, at
    the register. With the price of gas, and Knowing the oil co's are
    robbing us, and the war is About Oil, I buy gas Very reluctantly, and
    like if being robbed, if a mugger only got Some of the money you had
    on you, you feel like you didn't get taken for That much, I try to
    give them as little as possible. I usually only drive 2mi/day.

    I smoke and smoke little filtered cigars that look like brown
    cigarettes, 20 to a pack. I get them at a wholesaler, and with No
    cigarette tax, they are costing me 1$/pk. Because the wholesaler is
    only open M-F 9-4PM, and because of my injury, I don't function that
    well in the daytime in traffic, I stock up. I never spent more than .
    90/ pack for cigarettes, since when the name brands got that high, I
    found a cheaper one at .60/. When they went up I found the little
    cigars for that much. When they hit ,90/ I found the brand I smoke now
    at .45/. I was buying 180 packs at a time, so I didn't have to make
    the trip in the day that often, and they are only 1mi away. Now they
    are up to 1$/, and I only buy 120 packs. As cheap as they are, it
    still is a struggle to part with the money.

    With my old car, if I fill up in NJ, I still run it down till the
    needed stops moving, and then I reluctantly buy more. Because I ran
    out SO many times when I was much worse, I carry a can of gas in the
    trunk. I haven't run the Sube down to see the light, but put 5$ in
    twice, and 10$ once, and 25 when in NJ. I thought about filling when
    in NJ, but have been going over more often recently, and to break in
    the Sube faster, I've taken some 100mi plus trips, to drive it in
    different areas, on different type roads, to get familiar with the car
    on them.

    Everything is a learning and relearning experience for me. When
    buying something I get jammed up if I feel I am spending 1$ more than
    need be. It is a challenge to find or get the best price. Ebay was
    driving me crazy, and making my heart race and head hurt when getting
    close to the end of the auction. With the damage I have, I started to
    worry about having a stroke or heart attack for a few $, so eased up,
    and pick a price I can live with, and go with that, win or loose.

    houndman, Sep 11, 2007
  17. houndman

    houndman Guest

    yea, I know about partial fills and condensation. I used to work with
    aircraft fuels in the air force. The fuels are filtered, and icing
    inhibitors take care of the water. That's why dry gas isn't necessary
    now, and fuel pumps don't have removable glass bowls to see the water
    and dirt collecting in them.

    houndman, Sep 11, 2007
  18. houndman

    David Guest

    Those fumes seem to be getting to you.

    Have you considered medical marijuana? Paxil?
    David, Sep 12, 2007
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