Is this possible? It seems I get more mileage when the line is past the F than when it is between E and F.

my mustang and my civic did this. probly just how its measured in the tank. I would think this is normal...correct me if im wrong.

It might actually be yer fuel sender gauge.

How old is yer car ?

I know my gauge swishes a lot. So I have to remember to use the TripOmeter as oppsed to the gauge to see how much gas i have left.

your tank is bigger on the top than it is on the bottom, so it takes longer for the gauge to go down because it has to go through more gas to move it down, while at the bottom it has a lot less so it takes a lot shorter time...

this is normal with 99% of the vehicles on the road today

EDIT: forgot to say that past F is actually going up the fuel line going into the gas tank, it's not part of the tank itself and doesn't register on the guage