My Mazda 6 diesel MPG

Discussion in 'Mazda' started by Giles, Oct 28, 2016.

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  1. Giles

    Giles New Member

    I did a 600odd mile trip across Europe and clocked 3.9 l/100km according to the dashboard display. This was mainly motorways were I averaged about 100kmh/65mph.
     
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  2. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I may be just a dumb American , but 100km/hour = 62 MPH , I reckon. Still , 3.9l/100km is pretty nice for a big comfortable car like the 6.
     
  3. Giles

    Giles New Member

    ah yes you're right! it was a rough guess:)
     
  4. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    60.3 mpg. Not bad. :D
     
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  5. RedylC94

    RedylC94 Well-Known Member

    You don't have to guess or approximate if you own a simple calculator and remember the definitions of the relevant units.

    (0.0254m/in)×(12in/ft)×(5280ft/mile)×(0.001km/m)= 1.609344 km/mi exactly.
     
  6. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    60.3 , not too bad. WCWD ?
     
  7. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Love those results Giles!

    Wayne
     
  8. thunderstruck

    thunderstruck Super Moderator

  9. BillLin

    BillLin MASS: 2018 Bolt EV and 2017 Prime

    or even easier yet... ask Google/Siri/Alexa/Cortana. I only use the first one, so ymmv.

    edit: and another one I learned a week or so ago, if you're ok with arithmetic:

    divide the litre/100km by 235.215 (rounded off however you like) to get the mpg. // edit: erroneous; see following replies //
     
    Last edited: Oct 31, 2016
  10. RedylC94

    RedylC94 Well-Known Member

    But that requires memorizing a seemingly arbitrary number of 6 significant figures which isn't a fundamental definition of anything, is useful only for this one specific "conversion," and still is only an approximation. Knowing and using basic definitions (as in my post #5), none of which have more than 3 significant figures, doesn't require memorizing anything so specialized, and is exact. You can recycle and rearrange the same definitions for many other purposes.

    That 235.21458... comes from

    (2.54*2.54*231*10000)/(12*5280), where

    2.54 cm = inch,
    231 cubic inches = gallon,
    12 inches = foot,
    5280 feet = mile.


    .
     
  11. BillLin

    BillLin MASS: 2018 Bolt EV and 2017 Prime

    This is the only equivalence that I don't keep in my head. There's no need to go beyond 3 digits for the purpose of an approximation. Quick and easy is the goal.
     
  12. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind


    Maybe I'm not so good with arithmetic , but it seems like that is backwards. I would divide the 235.xxx number by the l/100km.
     
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  13. BillLin

    BillLin MASS: 2018 Bolt EV and 2017 Prime

    You got me, Edwin. What I see in my mind is 1 l/100 km = 235.xxx mpg and go from there with an inverse relationship.
     
  14. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I looked it up once and put it in my MPG spreadsheet. Now I just use that formula and don't think about the math.
     
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  15. RedylC94

    RedylC94 Well-Known Member

    That's inversed! 1L/100km = 1 gallon/235.xxx miles. Edwin's way works.

    NOTE: Edited to to add the missing "100," my error.
     
    Last edited: Nov 3, 2016
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  16. BillLin

    BillLin MASS: 2018 Bolt EV and 2017 Prime

    I was sloppy and should not have used the mathematical equal sign. You've proven the inverse relationship that I intuitively attributed to the conversion. Thanks. :D

    Edit: more thoughts... so some numbers I'm starting to use to get a feel for l/100km...

    Edwin keeps the numbers below around 3.6-3.9 l/100km for his daily commute.

    Most normal people driving normal ICE cars are doing well keeping below 5 l/100km. (mid-40s mpg).
     
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  17. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    When I first got my Scangauge , I set it up for l/100km and used it that way for a few months. I can understand it pretty well , but it made recordkeeping a bit more difficult , seeing as how we buy fuel in gallons here.
     
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  18. BillLin

    BillLin MASS: 2018 Bolt EV and 2017 Prime

    Yes, we seem to be a bit stubborn that way... despite being taught the metric system and scientific disciplines using metric, our daily lives still revolve around standard units.
     
  19. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    For most of the world, the metric system is the standard. We are the oddball outcasts who insist on doing everything the hard way.
     
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  20. BillLin

    BillLin MASS: 2018 Bolt EV and 2017 Prime

    So,... fantastic results. Can you tell us more about the conditions and techniques you used, or was it just a flat, single, bladder-busting 10 hour drive with cruise control on at 100 kph? ;)
     

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