I usually try to wait till 1/2 or less, with erratic fuel gauge I don't want to risk running out. I don't really try to guess when gas may go up/down, cause I'm gonna need it regardless of the price on any particular day.
After dropping off 2 of my kiddos at their schools, I commute to work and still have some time left over. This is when I fill up: in the mornings, same station, I even try to get the same pump if possible, same octane, etc... I try to keep it same to help eliminate any possible variables when filling up.
I also try to top off each tank, all the way up so I can see the gas at the flapper thingy in the filler hole. This way I know I have a FULL tank. I have noticed that even at the slowest notch on the handle, that the remaing amount I can squeeze in can vary from 1 to 2.5 gallons.
So.... I guess my new questions related to fillups are...
1 - Is topping off a good/safe thing to do to keep an accurate record of fuel used?
2 - Are there alternatives to topping off to be accurate?
3 - Would there be be any possible safety/mechanical/other drawbacks to topping off?
4 - Any other questions somebody else might have........?
I know gas pump police put the warning on the handles to try and keep me from doing this, but I guess I'm just a little rebelious sometimes
p.s. And, to expand on what Frank said about screwing around at the gas station more times, more stops give me more chances of buying that extra gatorade and snickers that I know I could do without
