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Better Measurement for Fuel Economy

Discussion in 'Off-Topic' started by civ_king, Aug 14, 2009.

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MPGJ or MPG, Read Below!

  1. MPGJ

    3 vote(s)
    18.8%
  2. MPG

    3 vote(s)
    18.8%
  3. Other

    8 vote(s)
    50.0%
  4. Radioactive Space Monkeys!

    2 vote(s)
    12.5%
  1. civ_king

    civ_king Deus Caritas Est

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    Would Miles Per Giga-Joule (MPGJ) be Better than MPG?
    With MPG you can only really measure for Gasoline which is fine now, but as we integrate electric and hydrogen cars into the system it becomes nigh impossible to accurately compare cars,

    how do you figure out how many Miles Per GALLON an electric car gets? or a hydrogen car for that matter, while a MPGJ will always be relevant regardless of energy type
     
  2. Earthling

    Earthling Deity

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    Doesn't matter - gasoline is not renewable and that's what we're concerned about. I'd say go with an entirely separate system for electric cars when the time comes. Also, hydrogen cars are rather infeasible and I can't see that changing until scientists invent magic.
     
  3. Cutlass

    Cutlass The Man Who Wasn't There.

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    You would have to do both. For the coming couple of decades most vehicles will still be fuel only. The other rating would be confusing. But I think you're on to something that there should be a comparative rating.
     
  4. civ_king

    civ_king Deus Caritas Est

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    why an entirely separate measurement for Electric, would one constant across the board be easier? if you have more than one type of power for vehicles?

    Why would it be confusing?
     
  5. Cutlass

    Cutlass The Man Who Wasn't There.

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    Because MPG is what people know. How do you compare a car not rated with your new system with one previous to that? Do both, fine. But don't drop MPG.
     
  6. GoodGame

    GoodGame Red, White, & Blue, baby!

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    MPG is already faulty. Things like driving style, tire pressure, even the brand/type of tires influences, condition of the components of the car, influence it's MPG over time. It's just a rough guideline. So it's really not that serious.

    Throwing in joules would just confuse it more since probably not all engines and fuel types will have comparable efficiencies. However, miles per non-renewable fuel joule might be useful for extending traditional comparisons to hybrids AND full electrics/hydrogens.
     
  7. Mise

    Mise isle of lucy

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    The best measure is CO2 per mile or CO2 per hour. And it should be measured and displayed on the dashboard of all new cars.
     
  8. Camikaze

    Camikaze Administrator Administrator

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    Personally, I think kilometres per litre would be better. ;)

    If don't know what the correlation is between fuel consumption and energy production, but it may not be perfect. Therefore, you may have a gas guzzler and a green car with far different levels of fuel consumption, but equal 'miles per giga joule'. This would be misleading.
     
  9. Jazzmail

    Jazzmail King

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    euros per kilometer is the most important measurement
     
  10. MagisterCultuum

    MagisterCultuum Great Sage

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    It seems odd to mix the Imperial and Metric systems like that.

    How about miles per foot-pound? Or maybe go ahead and simplify that to pound^-1 :p
     
  11. tycoonist

    tycoonist Deity

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  12. Fugitive Sisyphus

    Fugitive Sisyphus Escape Artist

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    For an electric car it seems that more important measurement is how many miles per per charge not how many miles/giga Joule. And even if were important we would measure it in miles/Kilowatt-Hour. :p

    Edit: oops the OP is talking about hydrogen cars not electric cars but my point still stands depending on how the hydrogen is produced.
     
  13. AngryZealot

    AngryZealot King

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    Cars should also be rated for how much energy it takes to make them. Some of the hybrids take enough extra energy that they are actually worse on the environment, even though they get better gas mileage.
     
  14. bhsup

    bhsup Deity

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    My latest issue of Car and Driver had a big article on this. The most likely outcome is to figure out a way to convert 100 miles per KWh to an MPG equivalent so consumers will be able to compare easily. But it's not anywhere close to being figured out and they may well go in a totally opposite direction.

    It was actually a very interesting article in general that also went into detail about how the current MPG ratings are determined. I highly encourage you to go find a copy of C&D to read it.
     
  15. Mise

    Mise isle of lucy

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    Both MPG and l/km are a bit silly as ratings for us in the UK, who fill up in litres and measure distances in miles.
     
  16. El_Machinae

    El_Machinae Colour vision since 2018 Retired Moderator

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    Apparently it's more intuitive to think in terms of 10,000 miles (or km) when comparison shopping.

    If we told you car A burnt 500 gallons for 10,000 miles, and the other car burnt 555 gal for 10,000 mi, you have an easier time figuring out costs than saying 18 mi/gal or 20 mi/gal
     
  17. AngryZealot

    AngryZealot King

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    I think I saw that same report. It's because upgrading from 20 mpg to 30 mpg isn't as good as upgrading from 10 mpg to 20 mpg, even though they're both an increase of 10 mpg. So a family with a sedan and a van will upgrade the sedan thinking it's better, when they really should upgrade the van.
     
  18. Bill3000

    Bill3000 OOOH NOOOOOOO! Supporter

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    tell that to the kilowatt hour
     
  19. emzie

    emzie wicked witch of the North

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    I think I also read the same article! It advocated doing [volume] per 100 [distance] which is how official fuel ratings are done here (though everyone still uses MPG it seems)
     
  20. Perfection

    Perfection The Great Head.

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    gasoline is sold as a uniform commodity. General "energy" is not, which makes cross platform comparisons as proposed not that useful for consumers. A person buying an electric car would want to know how much electric power it will take to charge up its batteries, a person buying a gasoline car would want to know how much gasoline it will take to fuel their car, neither would be especially concerned with the total physical energy content needed.

    I don't care how many joules my car takes; I care how much gas it takes.
     

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