Fuel consumption

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Mon 27 Oct 2003 13:51
Fuel consumption - Peter
On the subject of fuel consumption, I normally use Shell products either Optimax or unleaded and on balance I get 45 MPG. for the last two weeks I have been using petrol from a local supermarket and driving in the same conditions the MPG was only 41.

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Mon 27 Oct 2003 16:10
Fuel consumption - chris p crisps ©
On the subject of fuel consumption, I normally use Shell products
either Optimax or unleaded and on balance I get 45 MPG.
for the last two weeks I have been using petrol
from a local supermarket and driving in the same conditions the
MPG was only 41.

I have commented on this before with similar findings to yourself, however it is simlpy not as clear cut as supermarket fuel is less ecconomical that others as I have proved over many years that it seems very pot luck what fuel you end up with.
chris
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Mon 27 Oct 2003 16:36
Fuel consumption - Marcos{P}
Does fuel consumption not alter with different atmospheric conditions?
ie. the colder the air the denser so more oxygen, bigger bang resulting in less fuel used per bang if you get my drift.
Would this affect peoples fuel consumption figures or not?
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Mon 27 Oct 2003 17:27
Fuel consumption - Tony N
Strictly speaking to take advantage of the extra oxygen in colder denser air, you would need to put in more fuel to maintain the correct A(Oxygen)/F ratio. Therefore fuel consumption would increase.
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Mon 27 Oct 2003 22:27
Fuel consumption - v8man
If your engine management is working correctly your fuel to air ratio should not be affected.
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Tue 28 Oct 2003 08:52
Fuel consumption - Tony N
If your engine management is working correctly your fuel to air
ratio should not be affected.


Which is exactly my point.

Any extra oxygen available because of cooler/denser air will mean extra fuel will have to be put in to maintain 14.7:1 a/f ratio.
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Tue 28 Oct 2003 17:23
Fuel consumption - superannuated rocker
Yes you are quite right. Consider a given throttle opening which normally gives you 30mph. If air is denser than normal, then the engine management system will increase the fuel supply. This will cause your engine to develop more power and your car to go faster. If you wish to drive at 30 mph you will reduce the throttle opening and reduce both air and fuel supplies as a result.
Overall this theoretically should return you to the same mpg figures.
SR
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Mon 27 Oct 2003 17:44
Fuel consumption - eMBe {P}
.. subject of fuel consumption ..>>


A sure way to prove or disprove all this is to do independent scientific controlled laboratory tests by the likes of Which? or Trading Standards.

Only then will you know the truth. Until then it is all anecdotal or emprical or urban-myths.
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Mon 27 Oct 2003 22:34
Fuel consumption - J Bonington Jagworth
So the cost will be about the same, presumably? My car goes further on LRP (the extra benzene, perhaps) but of course the price differential varies a bit.
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