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Today’s tip is in regards to several emails I have received about filling up your gas tank only quarter or half way.
Fill up your gas tank all the way each time you go to the gas station.
The logic behind filling up your tank only a quarter, half or three quarters of the way isn’t faulty – by putting less gas in your car you’re reducing the amount of weight your vehicle is carrying around, thus increasing gas mileage.
While the logic isn’t faulty, the practice of not filling up your gas tank all the way more than likely is.
By not filling up your gas tank all the way, naturally you will have to take more trips to the pump, needlessly wasting gas.
Additionally, every time you remove your gas cap to add fuel to the gas tank, vaporized gas escapes from your tank. As I stated in a previous Fuel Economy Tip, over 147 million gallons of vaporized gas escape from gas tanks each year, so the less often you remove your gas cap, the better.
So, I would say that at the very least, the amount of money you save by driving around less weight is negated by the money you’ll lose by making extra trips to the pump and vaporized gas you’ll lose each time you remove the gas cap.
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“naturally you will have to take more trips to the pump, needlessly wasting gas.”
Not “naturally”, plan your trips (A tip of yours I believe). The station I use is one a corner I pass everyday, pull in and fill up added distance 50 ft maybe. No reason you can’t do the same.
“As I stated in a previous Fuel Economy Tip, over 147 million gallons of vaporized gas escape from gas tanks each year, so the less often you remove your gas cap, the better.”
How many cars are there on the road? With over 200 million vehicles in the United States (assuming your stat of 147 million is for the US only, is it?) That’s less than a gallon per car per year, .73 gallons/car/year.
That’s about .015 of a single gallon per fill up assuming weekly fill ups. That isn’t a ratio like 100lbs = 1% improved efficiency.
SO let’s see:
Fill to half tank: You go to fill up, you lose .015 gallons. Average gas weight of quarter a 10 gallon tank (40 lbs.) You lose a single .015 gallon by evaporation but gain a TOTAL of .03% for weight savings. NET of .015 gallons.
Fill to full tank: You go to fill up, you lose .015 gallons. Average gas weight of ½ a 10 gallon tank (80 lbs.) You lose a single .015 gallon by evaporation but gain a TOTAL of .02% for weight savings. Net of .005 gallons.
Bigger tanks only add to the savings.
The above is WORSE case assuming as you have that that: ALL the evaporated gas is lost at time of fill up, and not lost over time due to lose gaskets (Untrue or you wouldn’t have used it as a previous tip). Nor does it consider the fact filling your tank up more means MORE evaporated gas/air into the outside air as the new liquid gas displaces it in the tank.
You really need to do the math/research on these things.
I completely agree with the person above and from my own experience I do save money only filling up half way.
When I have a full tank the first half of gas will drop in a couple of days, the second half however can last me a week. I don’t have to go out of my way looking for stations to fill up, wasting mileage as I fill up right next to where I work. I would much rather making the savings stated in the comment before me than the ones you claim work.
is it true that vapourisation is more in a half tank than in a full tank