If I had say a petrol Ford with a V8 and 4.6L and the car did 30MPG over a 300 mile journey and say I had another Ford that was 4 cylinder and small (say Focus or Fiesta) and that also did 30MPG over exactly the same distance (300 miles) would the V8 puff out more CO2 per 30 MPG than the smaller 4 cylinder car?
Do different cars output different amounts of CO2 even if they use exactly the same amount of fuel over a given distance? I ask this because I did 300 miles in the Mustang V8 and achieved 30.2 mpg and did exactly the same journey in the CRV and got 30.1 mpg. So I was thinking is there only a certain amount of co2 you can possibly get from burning one litre of petrol or not.
The Mustang was marginally more economical than the CRV on this trip :)
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No the 30MPG fiesta used 1 gallon over 30 miles
The 10 MPG mustang used 3 gallons over 30 miles
So mustang co2 3 times more than fiesta
No mustang willdo 30MPG, my 2.0 audi only manages that with a light foot
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I'm afraid you are wrong as it does 30MPG on a run and this is my point people think they are gas guzzlers and they are not necessarily.
The Mustang is a 2006 vintage
So I must assume that at 30MPG they omit the same amount of CO2 per mile.
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Perhaps a car capable of 50mpg but doing 30mpg because of some sort of problem emits more CO2 than a car doing 30mpg in good order, and therefore this encourages you to keep your car in good condition?
Edited by Focus {P} on 19/02/2008 at 15:08
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CO2 is not calculated;it is recorded during the fuel cosumption tests.
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CO2 is measured during the emissions tests, and the fuel consumption is calculated from that.
It therefore must follow that, in the unlikely event a Mustang and a Fiesta where both doing the same MPG, then the emissions would be the same.
Most cars actually do emit CO2 a fair bit higher than the tests - in fact AutoExpress measured a Focus and found it really should be 2 groups higher than its rated level.
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Fuel consumption and emission tests are driven to a similar drive cycle but are not the same test;for example,the emission test is from a "cold" soak"-minimum of six hours and engine temperature must be between 20-30c. and within 2c. of ambient;fuel tests are from hot starts and the vehicle specs. will not necesarilly be the same.
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A fixed amount of petrol burned is a fixed amount of CO2 out the exhaust. Since three way cats are pretty efficient (especially on a run) you can more or less assume now that all the carbon in the petrol becomes CO2. Therefore it's possible for someone on a run in a V8 to put out much less CO2 than someone hammering a 1.2 around town.
It's also why tax based on CO2 output on the "official" test is a fallacy because most people with V8s don't drive them daily so in practice output less CO2 than their Focus TDCi neighbour with the 100 mile daily commute. The problem only becomes significant when a person drives a Cayenne Turbo as their everyday car. Oddly enough those people are rarely the ones doing 25k a year.
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cjehuk
You are so right my Mustang did around 2000 miles last year mostly on long motorway runs and the odd car show and it is quite economical considering the size of engine. My other car does around 8000 miles since my office moved nearer my home.
I see scores of small hatchbacks driven around with high revs smoke coming out and I wonder why the larger engines that are being driven sedately are being (sometimes unfairly) victimised.
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Any time a blunt instrument is used to attempt to regulate things like this the same problem will crop up. The intention of current legislation is to use the argument of CO2 emissions reduction (which I agree with) as a method of increasing taxation (which I don't). On the standard "EU" tests a vehicle with a large engine will (generally) do badly because for most of the test the engine is running at its least efficient, while smaller engines run right where they are most efficient - fairly heavily loaded with little in reserve. In the real world where power needs are generally considered higher, the smaller engine spends much of its time running harder at high revs to keep up with the larger engines that are running at their most economical.
The only way to ensure that CO2 reduction is the aim is to have a low registration fee for all cars e.g. £50 per year and then place all the remaining duty on fuel at say 60p/litre (up from the current 52p). Then the person doing 10k in a 40mpg car has an annual tax bill of £681.90 and the person doing 5k in a 20mpg car has a tax bill of.... oh £681.90, so that would be in proportion to the pollution caused then? Rational - Use less, pay less and allows members of our population to decide how they want to use less, by travelling less or by having a more economical car.
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The only way to ensure that CO2 reduction is the aim is to have a low registration fee for all cars e.g. £50 per year and then place all the remaining duty on fuel at say 60p/litre (up from the current 52p).
cjehuk, I agree but it is far too sensible for this government!
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