My interest in the CO2 debate was warmed by the loading for band G at £400 - seems fair enough
But - I have an Audi A6 2.7TDI - my usual economy is around 45mpg - today I did 300 miles at 49mpg. Why am I band F - very grateful not to be band G of course! - but surely 45mpg is about average (better than average?) for CO2 emissions?
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I would certainly say the mpg and CO2 emissions are connected, but I very much doubt it's as as easy as saying x mpg = y CO2. There'll be far more variables than that. So you having got good economy from a car doesn't necessarily mean the emissions are low.
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surely thats exactly what it means?
Diesel = CO2, less diesel = less CO2
If the car is banded on CO2 (as seems to be the case) and not on CO, other nasties, particulates etc, how are the other bits factored in?
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surely thats exactly what it means? Diesel = CO2, less diesel = less CO2 If the car is banded on CO2 (as seems to be the case) and not on CO, other nasties, particulates etc, how are the other bits factored in?
Most of the combustion products, petrol or diesel, are water, CO2, and CO ISTR + a few odds and ends, so
I agree (unless anyone knos better!)....
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Economy (mpg) is almost directly proportional to CO2 - the non-CO2 emissions make a pretty negligible difference, maybe 1-2% difference at most.
But diesel produces a fair bit more CO2 per gallon than petrol - something like 15% more.
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Economy (mpg) is almost directly proportional to CO2 - the non-CO2 emissions make a pretty negligible difference, maybe 1-2% difference at most. But diesel produces a fair bit more CO2 per gallon than petrol - something like 15% more.
So what's the rest, then? Both fuels are hydrocarbons - H + C + O AFAIK = the same old stuff. If petrol produces more CO2, what extra does diesel produce, & why? When I were a youth, the only engines allowed in force-
ventilated areas were diesel, but that was only because they would produce negligable CO.....
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All things being equal, diesel cars typically produce less CO2 than petrol cars per kilometre. They produce higher levels of NOX and particulates though. A litre of Diesel contains more energy than a litre of petrol - hence diesel cars being more "economical" in terms of mpg and having a lower CO2 output per km.
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I assume the lower CO2/km of a diesel, other things being equal, is due principally to higher thermal efficiency rather than the difference in energy content of the fuel?
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I assume the lower CO2/km of a diesel, other things being equal, is due principally to higher thermal efficiency rather than the difference in energy content of the fuel?
It actually both - although the energy content of the fuel does vary according to its derivation (e.g. biodiesel).
Broadly speaking though, the OP is correct in that a litre of petrol or diesel will give roughly (say to within 10%) the same amount of CO2 emission.
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When you go to a pub most drinks are forced with up with co2 the volume of co2 used by the drinks trade and commercial users is in excess of the the c02 produced by private vehicles are we to see emissions trading and offsetting when people by a pint or a coke.
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Ok we are agreed, mpg = CO2 more or less - so why am I in band F with 45mpg - do all the band A cars do 200mpg? the band B 150 mpg? - surely the best carbon tax is just to load it onto fuel duty - then the scamps that dont buy a tax disc would have to pay - even the worst criminals drive flash cars and spend lots on petrol - seems ideal to me.
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You're in band F because that's what the car emitted on the government cycle. The CO2 figures are a farce, it's more or less directly proportional. Your car on EU average gets 39.8mpg which equates to 190g/km of CO2. At 45mpg you're ACTUALLY producing about 165g/km, but the government can't tax you on how you drive (yet). By the same token an EU cycle on a focus ST is 30.1mpg and 224g/km, while most people are getting 22.2mpg which is oooh about 295g/km of CO2.
For the same MPG a diesel will produce more CO2 than a petrol because there is more carbon in diesel (it's a denser fuel), but a diesel will burn less fuel in the same car so comes out better.
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VED is a very minor part of motoring costs. I'm quite happy for my car to be in band F in exchange for the pleasure it's performance gives me.
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L\'escargot.
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>>but the government can't tax you on how you drive (yet).>>
Oh but they can, they do, and they have been for years!
That is what fuel excise duty is, hence if a Focus ST and an A6 2.7TDi are in the same VED band the leadfooted ST driver will pay a lot more tax that the snaily (not you L'escargot) A6 driver.
The problem is that the system is to complicated with questionable excuses to tax the motorist at every corner.
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This is not directed to anyone in particular, but .........
.......... just compare the weekly cost of VED with all the other motoring costs and (perhaps more importantly) what you fritter away on cigarettes and alcohol etc and you'll wonder why you were making such a fuss about VED!
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L\'escargot.
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As an aside, where do vehicles converted to run on L.P.G. fare in both emissions and tax banding. ?? The sort of vehicle I had in mind is a 4.4 litre petrol V8 Range Rover converted to L.P.G.
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.......... just compare the weekly cost of VED with all the other motoring costs and (perhaps more >> importantly) what you fritter away on cigarettes and alcohol etc and you'll wonder why you were >> making such a fuss about VED!
Quite true, especially compared to first year depreciation. That doesn't stop it being irksome because it's a crude piece of gesture politics, and a cynical political calculation; that all Band G drivers are cruising around in +£30k motors, can well afford to be soaked and wouldn't be idiot enough to vote Labour anyway. Only the last part is true in my case.
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