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Using MPG is annoying...

Discussion in 'Gen 3 Prius Fuel Economy' started by BigRedDarren, Dec 5, 2012.

  1. qbee42

    qbee42 My other car is a boat

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    It's more than Imperial vs SI, which is the real name for the metric system. Regardless of the units, there is the whole issue of numerator and denominator, with each side vilifying the other like the Big-Endians vs Little-Endians of Gulliver's Travels. Is it distance per fuel or fuel per distance. Both convey the same information, but one is more convenient than the other depending on the task at hand. Fuel per distance, as in MPG, is convenient for calculating the remaining range in the tank. The inverse is easier if you want to calculate how much fuel it will take to get somewhere. What it comes down to is that most people find multiplication easier than division.

    As an engineer, I'm used to units and unit conversions. Engineers have an old saying that factors are always specified in the least convenient units. Distance, for example, in furlongs per fortnight. You get used to converting them, but in general the arithmetic is a lot easier in SI.

    Tom
     
  2. Les_PL

    Les_PL Active Member

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    Not exactly - slightly modified, i.e. speed by SI is [m/s] :)
     
  3. bisco

    bisco cookie crumbler

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    i like mpg's, the more m's the better!:p
     
  4. Former Member 68813

    Former Member 68813 Senior Member

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    Are you saying US folks were too lazy or too dumb back in 70's to learn metric?

    Isn't US the only country stuck with gallons? Wait, not really:

    Imperial units - Wikipedia, the free encyclopedia
     
  5. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Actually we've gotten lazier and dumber as a country since the 70's..... ;)

     
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  6. BigRedDarren

    BigRedDarren New Member

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    Yes, the sticker on the Prius in the showroom said 72MPG which is 3.2L/100km if you assume it's a US MPG (which for my location should be a good assumption since we're 15 minutes from the US border).

    My average in the first 1,000km is 5.49L/100km which is 42.8 MPG (US). No where close to the 72MPG sticker that was on the car. But it's cold and wet here, I have been playing with the car, and the wife doesn't try to drive efficiently.

    ;D
     
  7. fuzzy1

    fuzzy1 Senior Member

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    That looks like a bad assumption.

    If it meant 72 I-MPG, that would translate to 60 US-MPG, which is what many of us believe the Prius would be rated on the old optimistic EPA scale that was retired in 2007. The Canadian scale is similar to that old US scale.
     
  8. xs650

    xs650 Senior Member

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    The US doesn't us the Imperial system it uses U.S Customary units. It's more tradition bound than the Imperial system. The US gallon is the Queen Anne's wine gallon of 1707, the Imperial system uses the Imperial gallon from mid-19th century. I've always suspected that the Brit beer louts switched to the Imperial system so their pints of beer would be bigger. I salute them.

    While S.I. is the most common metric system, it isn't the only one actually used. While working on international projects I learned that some countries really butcher the metric system to the point that it is no longer SI. Using kg as force is one of the more common ones, it's longer SI when you do that.
     
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  9. Les_PL

    Les_PL Active Member

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    Kilogram-force [kG or kgf] never pretended to be a part of SI. Yet it is widely used - one of examples is a definition of metric Horse Power [PS].
     
  10. qbee42

    qbee42 My other car is a boat

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    Using mass units for force is one of my pet peeves. The other way around bothers me as well. Unfortunately, nature refuses to cooperate with the concept of well behaved units and nice round numbers. Why did she stick us with 365 days in a year and 6.02x10^23 atoms in a mole? It's all very inconvenient.

    Tom
     
  11. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    ^ I'm not a engineer or a scientist....but the last time I killed a mole it looked like it should have more atoms in it than that.

    Do they make them really really small up there in Michigan?
     
  12. qbee42

    qbee42 My other car is a boat

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    No, but we do have big atoms.

    Tom
     
  13. xs650

    xs650 Senior Member

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    LOL, that's one of the more egregious violations of SI purity and I had never considered it.
     
  14. cwerdna

    cwerdna Senior Member

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    Hehe.... as I mentioned, Google makes for a great unit converter, in most cases. One can Google for 10000 furlongs per fortnight in mph and it'll give you the answer. One of my favorites is to do 50 mpg in teaspoons per mile.
     
  15. xs650

    xs650 Senior Member

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    That would be small, a shot of whiskey is about 2.5 moles.
     
  16. Corwyn

    Corwyn Energy Curmudgeon

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    Human Body Temperature. Yes it is.

    When was the last time you needed to measure the temperature of boiling water?...
     
  17. Corwyn

    Corwyn Energy Curmudgeon

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    Instead of Miles per gallon, convert it all to inches and get 13,714 inches^-2!

    OR take the inverse and get 0.0000729 square inches which is the cross section of a line of gasoline as long as your trip, containing the volume of gasoline you used to traverse it.
     
  18. cwerdna

    cwerdna Senior Member

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    Kinda on this note, note the user name of the OP of Tyre Pressure | PriusChat. :) Using kilopascals for tire pressure for us Americans is also TOTALLY useless. 35 psi? Now that means something to me.
     
  19. tach18k

    tach18k Member

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    Hey, like in soccer, Soccer started outside the USA, but the demensions used all over the world are in yards and not meters, go figure.
     
  20. xs650

    xs650 Senior Member

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    Soccer as we know it started in England before they were metrificated.