Hi MetroMPG

Ime not sure of the exact size of my tank.
The most I have ever fit is 36 litres into it rite up the tube , so perhaps its 35 litres in size but probably it is 40.

¨I always try to fill at the samp pump, parked in the same spot - that's the key.¨

I agree , it is a must , supossing a tank does have an air trap filling up at the exact same pump (whatever the floor level may be) and addopting the same fill method will get far more consistant results.

My next fill up should give a good baseline indication of what my cars FE is.
As its slightly different in specs to the average metro I have no figures available from others experience., and my Suzuki handbooks FE figure seems very optimistic.

I think I will come in at a lower FE number than what they quote.

Hi theclencher

Yeah , i saw that thread b4., but I dont think it address the exact point that I have raised here.
But even when estimating how far up our filler neck the gas ends at could introduce another variable that would be especially noticable with small fills.

A scribed mark on the inside of the tube might be a good guide as to fuel height instead of just relying on memory.

Might need to reinvent the fuel stick like what was used in old VW's :-)

Hmm, i was just thinking about this, I also have the same problem, but mines even worse because I mix my own fuel, E-42.5, so I never fill it up to the same levels :S. Not to mention my fuel gauge hasn't moved since my last boost tuning run.

Anyways, the problem i see is if you fill up with gas in the morning, it's colder-denser, the pump measures volume, but the engine injects it by mass, (1g of gas does 1g of gas's work.) So if you fill up one day when its cold, and one day when it's hot you could have a noticeable difference in the actual amount of gas your getting!

Yawwwn , I still have about 50 miles left in my tank before i will refill.
At my usage rate thats another 2 , maybe 2 and a half weeks. :-(

Big oil doesnt have much of a grip on me ,, well ,, if I ignore transport costs on the good that I buy that is.