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How can you determine your cars CO2 emissions per Km?

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  • 13-03-2009 2:44pm
    #1
    atlantean
    Registered Users Posts: 556 ✭✭✭


    I was just wondering how one could determine their cars actual CO2 emissions. I have just had my car NCT'd and it had no problem with the emissions test but it does not give a g/Km result.

    All new cars have a g/km figure on which their VRT and road tax is calculated from. I was wondering how my old car would compare with these.

    Is there a simple formula that can be used?
    Tagged:


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    #2
    Anan1
    Registered Users Posts: 22,815 ✭✭✭✭Anan1


    I'd imagine CO2 emissions are directly related to fuel used?


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    #3
    atlantean
    Registered Users Posts: 556 ✭✭✭atlantean


    True, and how well it is actually burned!


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    #4
    BlackWizard
    Registered Users Posts: 3,282 ✭✭✭BlackWizard


    entire rain forests are disappearing because the rely on the CO2 that our cars produce. You are killing off the trees :mad:

    Edit: I.e stop worry about CO2.. just keep producing it to keep the trees happy


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    #5
    Anan1
    Registered Users Posts: 22,815 ✭✭✭✭Anan1


    BlackWizard wrote: »
    entire rain forests are disappearing because the rely on the CO2 that our cars produce. You are killing off the trees :mad:
    ?? Rain forests absorb CO2, producing oxygen and storing the carbon in the wood, no?


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    #6
    alias no.9
    Registered Users Posts: 6,310 ✭✭✭alias no.9


    atlantean wrote: »
    I was just wondering how one could determine their cars actual CO2 emissions. I have just had my car NCT'd and it had no problem with the emissions test but it does not give a g/Km result.

    All new cars have a g/km figure on which their VRT and road tax is calculated from. I was wondering how my old car would compare with these.

    Is there a simple formula that can be used?

    The NCT emissions test has nothing to do with CO2. It checks CO and unburned hydrocarbons, essentially checking that your engine is in tune and your catalytic converter is working. To find the official figures for your car, try www.smmt.co.uk and to do the real calculations for yourself, for every litre petrol consumed, approximately 2.38kg of CO2 is produced, the figure for diesel is 2.65kg.


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    #7
    BlackWizard
    Registered Users Posts: 3,282 ✭✭✭BlackWizard


    alias no.9 wrote: »
    for every litre petrol consumed, approximately 2.38kg of CO2 is produced, the figure for diesel is 2.65kg.

    Is this really true? Seems like a lot of CO2


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    #8
    Mr Benevolent
    Closed Accounts Posts: 12,456 ✭✭✭✭Mr Benevolent


    Is this really true? Seems like a lot of CO2

    Let's see:

    Assume a 1.9TDI engined VAG producing 147g/km

    Fuel efficiency would be @ 50mpg or 17.8 km/litre

    Diesel weighs about 900g per litre (specific density)

    So 1kg of diesel = 1.10 litres

    17.8 * 1.10 = 19.6km

    19.6 * 147 = 2.878kg

    Close enough...


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    #9
    galwaytt
    Registered Users Posts: 12,776 ✭✭✭✭galwaytt


    atlantean wrote: »
    I was just wondering how one could determine their cars actual CO2 emissions. I have just had my car NCT'd and it had no problem with the emissions test but it does not give a g/Km result.

    All new cars have a g/km figure on which their VRT and road tax is calculated from. I was wondering how my old car would compare with these.

    Is there a simple formula that can be used?


    Short answer, no.

    The CO2 g/km figure you're referring to is calculated according to a particular ISO standard, which involves certain speeds etc etc.. You can't work back to that, for a car that was never tested to that standard.

    The problem with using fuel actually used and the CO2 produced during it's combustion is, that if you used that formula, the new 'green cars' wouldn't be half as green as they're made out to be.........and that wouldn't suit a bunch of people......

    Rest assured, that if you have an older car, that is clean on CO2 on idle, doesn't burn oil, and is running well, that, by keeping it on the road for as long as possible, you are de facto making a bigger contribution to NOT producing CO2 compared to ANY new car, due to you not incurring any CO2 in manufacture of a replacement vehicle.

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



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    #10
    Anan1
    Registered Users Posts: 22,815 ✭✭✭✭Anan1


    Confab wrote: »
    Aren't the two of you saying the same thing?
    No - BlackWizard is saying the CO2 is killing the trees, i'm saying they're using it to grow.


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    #11
    alias no.9
    Registered Users Posts: 6,310 ✭✭✭alias no.9


    BlackWizard wrote: »
    Is this really true? Seems like a lot of CO2

    Example: Fiat 500 1.2 petrol 55.4mpg / 119g CO2/km
    55.4mpg / 0.62 = 89.35 km/gallon
    89.35 km/gallon / 4.55 = 19.64km/l
    19.64km/l * 119g CO2/km = 2337.16g CO2/l = 2.34kg CO2/l

    The figure I quoted above is averaged over a range of cars.


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    #12
    siralfalot
    Closed Accounts Posts: 447 ✭✭siralfalot


    Just buy a V8 and forget about silly and irrelavent things like CO2 :D


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    #13
    unkel
    Registered Users Posts: 65,414 ✭✭✭✭unkel
    Chauffe, Marcel, chauffe!


    BlackWizard wrote: »
    Is this really true? Seems like a lot of CO2

    Yep. You can work it out the other way around. Say an average petrol car emits 160g of CO2 per km. With a fuel consumption of 15km/l (40MPG) this amounts to 15*160 = 2.4kg for the one kilometre

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    https://www.adverts.ie/member/5856/ads



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    #14
    Anan1
    Registered Users Posts: 22,815 ✭✭✭✭Anan1


    BlackWizard wrote: »
    Is this really true? Seems like a lot of CO2
    I'm no chemist, but if every carbon molecule bonds to two oxygen molecules to make CO2 then the weight sounds about right.


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    #15
    sparklepants
    Closed Accounts Posts: 107 ✭✭sparklepants


    A lot easier than all of the above.

    Petrol emits 2.33 kg CO2 per litre consumed
    Diesel emits 2.68 kg CO2 per litre consumed

    Just track the amount of fuel you use and the CO2 calculation is easy.


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    #16
    sparklepants
    Closed Accounts Posts: 107 ✭✭sparklepants


    unkel wrote: »
    Yep. You can work it out the other way around. Say an average petrol car emits 160g of CO2 per km. With a fuel consumption of 15km/l (40MPG) this amounts to 15*160 = 2.4kg for the one litre
    Corrected that for you!


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    #17
    Dartz
    Registered Users Posts: 4,373 ✭✭✭Dartz


    Who cares?

    Really, truly. The green party? They're a bunch of blithering idiots who I wouldn't deign to waste a bullet on. I don't believe Co2 harms the planet or causes climate change. It'll bloody well do that on it's own, no matter what we do here.


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    #18
    Mr Benevolent
    Closed Accounts Posts: 12,456 ✭✭✭✭Mr Benevolent


    I'm confused now. Is it per kg or per litre? There can be big differences because of different specific gravities.


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    #19
    Anan1
    Registered Users Posts: 22,815 ✭✭✭✭Anan1


    Dartz wrote: »
    Who cares?

    Really, truly. The green party? They're a bunch of blithering idiots who I wouldn't deign to waste a bullet on. I don't believe Co2 harms the planet or causes climate change. It'll bloody well do that on it's own, no matter what we do here.
    I can't imagine climate change much cares what you think either, TBH.


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    #20
    sparklepants
    Closed Accounts Posts: 107 ✭✭sparklepants


    Confab wrote: »
    I'm confused now. Is it per kg or per litre? There can be big differences because of different specific gravities.
    ...
    sparklepants wrote: »
    A lot easier than all of the above.

    Petrol emits 2.33 kg CO2 per litre consumed
    Diesel emits 2.68 kg CO2 per litre consumed

    Just track the amount of fuel you use and the CO2 calculation is easy.


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    #21
    Mr Benevolent
    Closed Accounts Posts: 12,456 ✭✭✭✭Mr Benevolent


    ahaaaaaa... light dawns :o


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