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Discussion Starter · #1 ·
I was out in the sticks today when I realised the tank was nearly empty. I limped to the local garage, 5 miles away, coasting part of the way with the engine off (not recommended for safety reasons, but it was a quiet country lane). A few miles from the garage and the needle was on zero, but I made it, somehow. 36 liters went in, with 452 miles elapsed, giving 57mpg. Apparently the tank holds 35 liters. Eh? No it doesn't, it holds at least 36 liters.
 

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Its got a reserve tank hasn't it? Thats how I understand it anyhow, theres a main fuel tank with 35 litres then a reserve tank and I guess thats 5litres! Thats what my golf had its what the works vans have and my mates audis so I just assume the up! Will be the same! And you have nearly proved it lol
 

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Itzben said:
Its got a reserve tank hasn't it?
"Reserve" isn't a physical thing or tank on most cars ... it's just the preset tank level where the light comes on.

Fuel tanks in cars aren't empty wen they show empty - the obvious reason for that feature usually sits behind the wheel.


Remember how far the Top Gear blokes drove on empty ?


Added to that, it's often possible (but not recommended) to fill up the evaporation / expansion volume that the tank's design provides for.
 

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Ye it was london to far end of scotland and back wasnt it 900 miles or so in a audi haha! I was always unsure weather it was 2 tanks or how you said (hope that didn't make me sound stupid lol) I get the feeling when mu up says half full/empty that I don't have long left, like my golf it takes ages to read 1/2 but then drops v fast as if the tank was cone shape lol
 

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up-down-under said:
how do you wanna know that you've got 36 literfrom the servo? you paid for 36 but did you get 36?

I agree, we all ASSUME that what we pay for at the pumps is actually what we are getting, but who actually checks?

Sure they are at least in some countries they have to get the pumpscalibrated(lacking correct word) every year or so to make sure its accurate, but we still don't actually know we get what we pay for...
 

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up-down-under said:
how do you wanna know that you've got 36 literfrom the servo? you paid for 36 but did you get 36?

it should also be considered that the density of gas os higher when its cold, so besides being cheaper in the mornings, its also denser so you get more energy with each liter. This is also part of the reason why your car will display a "better" milage when running on cold nights, as it needs to draw in less gas (by volume) to get the same combustion values.
 

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Discussion Starter · #12 ·
Mulo said:
up-down-under said:
how do you wanna know that you've got 36 literfrom the servo? you paid for 36 but did you get 36?

it should also be considered that the density of gas os higher when its cold, so besides being cheaper in the mornings, its also denser so you get more energy with each liter. This is also part of the reason why your car will display a "better" milage when running on cold nights, as it needs to draw in less gas (by volume) to get the same combustion values.
Actually cars use more fuel on cold days, they take longer to warm up, consuming more fuel while they do so, and the air is denser. Also they change the formulation of the fuel slightly in Winter.

I am consistently getting 57mpg at the moment, using various garages. I got 65+mpg in Summer.
 

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Mulo said:
up-down-under said:
how do you wanna know that you've got 36 literfrom the servo? you paid for 36 but did you get 36?

it should also be considered that the density of gas os higher when its cold, so besides being cheaper in the mornings, its also denser so you get more energy with each liter. This is also part of the reason why your car will display a "better" milage when running on cold nights, as it needs to draw in less gas (by volume) to get the same combustion values.

Firstly, HMRC Weights and Measures check the calibration of pumps dispensing petrol every 6 months. Given the amount of VAT and Duty on fuel, the Government are VERY careful to regularly check pumps are dispensing correctly" ;) The way a petrol pump works is that the counters are fed using impellors in the fuel line, meaning that they are only driven when liquid is passing through them. It is impossible for a petrol pump to register air as fuel.

Secondly, the old 'myth' about fuel being 'cheaper' in the mornings is nothing more than that - a myth. Whilst it is true that gas is more dense when cold, petrol is a liquid, and differences in temperature affect petroleum liquid density in a micro-measurable way. More importantly, petrol tanks are buried beneath the ground, where temperature differences are minimal, regardless of the air temperature above ground.
 

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shakotanVIP said:
Mulo said:
up-down-under said:
how do you wanna know that you've got 36 literfrom the servo? you paid for 36 but did you get 36?

it should also be considered that the density of gas os higher when its cold, so besides being cheaper in the mornings, its also denser so you get more energy with each liter. This is also part of the reason why your car will display a "better" milage when running on cold nights, as it needs to draw in less gas (by volume) to get the same combustion values.

Firstly, HMRC Weights and Measures check the calibration of pumps dispensing petrol every 6 months. Given the amount of VAT and Duty on fuel, the Government are VERY careful to regularly check pumps are dispensing correctly" ;) The way a petrol pump works is that the counters are fed using impellors in the fuel line, meaning that they are only driven when liquid is passing through them. It is impossible for a petrol pump to register air as fuel.

Secondly, the old 'myth' about fuel being 'cheaper' in the mornings is nothing more than that - a myth. Whilst it is true that gas is more dense when cold, petrol is a liquid, and differences in temperature affect petroleum liquid density in a micro-measurable way. More importantly, petrol tanks are buried beneath the ground, where temperature differences are minimal, regardless of the air temperature above ground.
Sounds about right to me - good informative post from skakotanVIP



Edited by: Truth-seeker
 

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In my old car (Landrover Defender 90) that done 22mpg you could do about 30-40 miles when the needle was at zero, the needle actually went a long way past zero haha
 
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