General Available mileage after fuelling

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General Available mileage after fuelling

Chrisgr

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I have noticed a difference between BP garages when i fuelling the car. I get 434 miles available, full tank, but today i went to a garage closer to my home to save some time. I got 401 miles on the trip computer.
My partner get the same result when she goes to Morrison's or shell, less mileage.There seems to be something "special" with the fuel quality in the BP garage where we usually go to.It does last longer as well, usually 2 to 3 days.
Any ideas?
 
Well I would think it is just a random variable that always happens to be favourable.

My 1st thought would be that the BP pumps are putting a little more fuel in before shutting off. The vehicles fuel gauge is not a high resolution instrument so when you fill a BP with a "better fill" the tank sender unit will be sending say 100 units. Your fuel gauge has 10 divisions. So the top bar/division is active for tank units 90+. At the other garages you may think you have filled up fully but possibly can't get more than 92 tank units into the tank. Car will still show full but the trip computer will calculate based on 92 units. i.e. 8% less.

Now just by sheer coincidence you example figures of 401 and 434 is 8% less.

As for fuel quality then at the point of fill-up this is irrelevant. Even if the car could measure the quality of the fuel (which it can't) then pipes from the tank and through to the injectors are full of the old fuel and not the new fuel put in. Worse still if the old fuel was returning poorer mpg then the trip computer could/would use this lower number to calculate range for the new fuel which you find does better MPG.

The only way to be sure is to brim fill to overflow which is difficult with modern cars/500X due to the self sealing flap and close/sealed tank filler neck to pump fuel nozzle.

Well this is my theory/explanation :)

Answers on a post card to "Chrisgr" care of "Fiat Forum"
 
Your range is also dependent on your driving over the previous x distance (I don't know what it is, but not many I should think). So if you sat in traffic, gave it a bootful, or spent time idling - this may have made the range lower. Even on the same apparently journey I do twice a day the fuel consumption changes as lots of small unnoticeable differences add up!
 
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