Keep the gas tank always at least half full of gas

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31. just to be devil's advocate, keeping your tank on the full side lowers fuel efficiency

if your carrying around an extra 8 gallons of gas, that's close to 50 extra pounds of weight (a gallon of gas is about 6.3 pounds), which reduces your miles per gallon by about 1%.

for most cars we're probably not talking about an extra 8 gallons.
filling up when your tank is half empty means on average you're driving with a tank 3/4 full.
fliling up when you get down to fumes means on average you're driving with a tank 1/2 fill.
the difference is 1/4 tank, which is only 8 gallons if your tank holds 32 gallons, which is a rather large tank.
f150 or hummer size. most tanks are smaller.

so the savings would be a bit less, but just to ball park it, figure you're increasing your gas costs by almost 1% by carrying around that extra gas.

you could save even more by not filling it up all the way, at the obvious expense of having to make more stops at a gas station.


for me it's not worth it, for convenience i fill it up all the way. when i get to about 1/4 tank i'll find a cheap gas station if it's convenient just to avoid the risk of *needing* to stop for gas when it's not convenient or cheap.