UK petrol sales down 20% in 5 years
#31
Be interesting to see the percentage in fuel price increase.
Re tax.
A customer has a dodge viper srt 10 truck. 8.0 litre and a corvette 6.2l both are under £250 a yr tax. !
Re tax.
A customer has a dodge viper srt 10 truck. 8.0 litre and a corvette 6.2l both are under £250 a yr tax. !
#35
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The relationship between the two depends on the fuel, not the vehicle. If you burn X amount of petrol to travel a mile, then the amount of CO2 produced is simply the amount of CO2 which is (always) released when X amount of petrol is burned.
Have a look here - there's a chart at the bottom of the page which shows the relationship between mpg and CO2/km for petrol and diesel.
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Fuel economy and CO2 emissions are just two different ways to measure one and the same thing. They're inextricably linked; all the carbon atoms that come out of a vehicle's tailpipe originally entered the vehicle via the fuel filler.
The relationship between the two depends on the fuel, not the vehicle. If you burn X amount of petrol to travel a mile, then the amount of CO2 produced is simply the amount of CO2 which is (always) released when X amount of petrol is burned.
Have a look here - there's a chart at the bottom of the page which shows the relationship between mpg and CO2/km for petrol and diesel.
The relationship between the two depends on the fuel, not the vehicle. If you burn X amount of petrol to travel a mile, then the amount of CO2 produced is simply the amount of CO2 which is (always) released when X amount of petrol is burned.
Have a look here - there's a chart at the bottom of the page which shows the relationship between mpg and CO2/km for petrol and diesel.
There is a rough link but there are definitely some cars good on mpg with poor CO2 emissions and vice versa.
#38
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Eh?
Fuel economy and CO2 emissions are both measures of quantity per unit distance. Time doesn't enter into the calculation.
There's quite a comprehensive discussion of the topic here - but the important thing to note is that the complete combustion of a litre of fuel produces a certain amount of CO2, so provided the car isn't chucking out significant amounts of CO and unburned hydrocarbons, mpg and g/km are just measures of the same thing.
They may, of course, be measured at different times and under different conditions for the purposes of tax and other non-scientific purposes, which will lead to a discrepancy - but that's just needlessly confusing.
Fuel economy and CO2 emissions are both measures of quantity per unit distance. Time doesn't enter into the calculation.
There's quite a comprehensive discussion of the topic here - but the important thing to note is that the complete combustion of a litre of fuel produces a certain amount of CO2, so provided the car isn't chucking out significant amounts of CO and unburned hydrocarbons, mpg and g/km are just measures of the same thing.
They may, of course, be measured at different times and under different conditions for the purposes of tax and other non-scientific purposes, which will lead to a discrepancy - but that's just needlessly confusing.
#40
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It tells you something about the *completeness* of combustion, ie. what proportion of the fuel that's burned ends up as carbon dioxide, but that's close to 100% in any modern engine. Unburned fuel results in CO and HC emissions which are oxidised by the catalytic converter, and levels are of course, very tightly limited by law.
That's not the same thing as efficiency, which is a measure of how much of the energy from the fuel is converted to useful mechanical work, as opposed to being lost as waste heat.
That's not the same thing as efficiency, which is a measure of how much of the energy from the fuel is converted to useful mechanical work, as opposed to being lost as waste heat.
#41
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This is my point
I suppose you could be getting at this as well. Does the mpg rating of a car correspond to the amount of CO2 produced? The answer to that is maybe. the actual Liters / mile depends on multiple factors. Like driving conditions (hills for example), whether or not you're using your air conditioner, the quality of your air filter, etc. A car rated for 21 mpg may actually only get 15 mpg while a car rated for 17 mpg may get 22 mpg...
A fuel efficient engine, with the corresponding low co2 emissions will not give very good fuel economy if used to power an Abrams main battle tank
I suppose you could be getting at this as well. Does the mpg rating of a car correspond to the amount of CO2 produced? The answer to that is maybe. the actual Liters / mile depends on multiple factors. Like driving conditions (hills for example), whether or not you're using your air conditioner, the quality of your air filter, etc. A car rated for 21 mpg may actually only get 15 mpg while a car rated for 17 mpg may get 22 mpg...
A fuel efficient engine, with the corresponding low co2 emissions will not give very good fuel economy if used to power an Abrams main battle tank
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Sure, if you drive a vehicle under different conditions, it'll use a different amount of fuel to travel a given distance - but then it'll also emit a different amount of CO2.
You can't create or destroy carbon atoms. All the carbon that goes into the car through the fuel filler has to go somewhere, and that 'somewhere' is out the tail pipe.
BTW a small engine in a large vehicle does actually give good economy, because the throttle will be more open more of the time - and that's good for the thermodynamic efficiency of the engine. It's precisely why small engined cars tend to be more economical than large engined cars, despite the fact that at large engine has a greater ratio of volume to surface area in the cylinders, with correspondingly reduced heat loss.
You can't create or destroy carbon atoms. All the carbon that goes into the car through the fuel filler has to go somewhere, and that 'somewhere' is out the tail pipe.
BTW a small engine in a large vehicle does actually give good economy, because the throttle will be more open more of the time - and that's good for the thermodynamic efficiency of the engine. It's precisely why small engined cars tend to be more economical than large engined cars, despite the fact that at large engine has a greater ratio of volume to surface area in the cylinders, with correspondingly reduced heat loss.
#43
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and surely "time" has a part to play in the whole fuel economy discussion because without "getting anwhere" which is measured in feet/sec or miles per hour the fuel economy debate is pointless
out of interest the CO2 fugures that are quoted are they measured whilst the car is moving (or simulated on rollers) or are they just a simple equation based on "we put this much fuel in and this much comes out the back" with the engine running at a set rpm
#44
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"Slick tyres are pumped hard to reduce rolling resistance. Brakes are adjusted, or at times even disconnected, to reduce friction. Cracks between body panels and windows are taped up to reduce air resistance. Sometimes they even remove the wing mirrors."
disconnecting the alternator, thus no energy is used to recharge the battery during the test
the use of special lubricants that are not used in production cars, in order to reduce friction
turning off all electrical gadgets such as the air-conditioning or the radio"
http://www.bbc.co.uk/news/business-21759258
disconnecting the alternator, thus no energy is used to recharge the battery during the test
the use of special lubricants that are not used in production cars, in order to reduce friction
turning off all electrical gadgets such as the air-conditioning or the radio"
http://www.bbc.co.uk/news/business-21759258
How they can get away with it, given the amount of EU rules and tax incentives there are now on fuel-economy standards for car manufacturers, is pretty astonishing.
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Fuel economy and CO2 emissions are just two different ways to measure one [B]and the same thing. They're inextricably linked; all the carbon atoms that come out of a vehicle's tailpipe originally entered the vehicle via the fuel filler.
The relationship between the two depends on the fuel, not the vehicle. If you burn X amount of petrol to travel a mile, then the amount of CO2 produced is simply the amount of CO2 which is (always) released when X amount of petrol is burned.
Have a look here - there's a chart at the bottom of the page which shows the relationship between mpg and CO2/km for petrol and diesel.
The relationship between the two depends on the fuel, not the vehicle. If you burn X amount of petrol to travel a mile, then the amount of CO2 produced is simply the amount of CO2 which is (always) released when X amount of petrol is burned.
Have a look here - there's a chart at the bottom of the page which shows the relationship between mpg and CO2/km for petrol and diesel.
LOL
dun
Last edited by dunx; 06 April 2013 at 06:40 PM.
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