I discovered these tips to get more gas for your dollar. Some of these ideas are pretty common knowledge- others may be new to you.

Only buy or fill up your car in the early morning when the
ground temperature is still cold. Remember that all service stations
have their storage tanks buried below ground. The colder the ground the
more dense the gasoline, when it gets warmer gasoline expands, so buying
in the afternoon or in the evening....your gallon is not exactly a
gallon. In the petroleum business, the specific gravity and the
temperature of the gasoline, diesel and jet fuel, ethanol and other
petroleum products plays an important role. A 1-degree rise in temperature is a big deal for this business. But the service stations do not have temperature compensation at the pumps.

When you're filling up do not squeeze the trigger of the nozzle to a
fast mode. If you look you will see that the trigger has three (3)
stages: low, middle, and high. You should be pumping on low speed,
thereby minimizing the vapors that are created while you are pumping.
All hoses at the pump have a vapor return. If you are pumping on the
fast rate, some other liquid that goes to your tank becomes vapor. Those
vapors are being sucked up and back into the underground storage tank so
you're getting less gas for your money.

One of the most important tips is to fill up when your gas tank is HALF
FULL or HALF EMPTY. The reason for this is, the more gas you have in
your tank the less air occupying its empty space. Gasoline evaporates
faster than you can imagine. Gasoline storage tanks have an internal
floating roof. This roof serves as zero clearance between the gas and
the atmosphere, so it minimizes the evaporation. Unlike service
stations, here where I work, every truck that we load is temperature
compensated so that every gallon is actually the exact amount.

Another reminder, if there is a gasoline truck pumping into the storage
tanks when you stop to buy gas, DO NOT fill up- most likely the gasoline
is being stirred up as the gas is being delivered, and you might pick up
some of the dirt that normally settles on the bottom.

Hope this will help you get the most value for your money.

 

Realistically, this is more theoretical than actual. Even at 6 to 7 feet below ground, the temperature is pretty constant. Hence, one day's external temperatures don't have a lot of impact on the temperature of the gasoline underground. (I remember working in gas stations in Iowa during the winter and it took weeks of winter weather before the gasoline started feeling any colder -- and even then it wasn't REAL cold.) About the only thing that can be affected by one day's changing temperatures is the pump itself and the hose going into your car. And say on a warm day at a high-volume station, the regular flow of gas from underground through a pump and its hose keeps the insides of the unit pretty well cooled off, so there actually isn't a lot of temperature change internally.

 

Of course w/ the Half Full/Empty tip, I would like them to test the amount of evap compared to the amount consumed to move the extra weight associated w/ 7 to 10 gallons (on average) of gasoline weight in that half full thing....

I save gas by only going down hill! Sure, it limits where I can go, but man I get great gas mileage!

 

The last one is the only one I have ever head before. I'll have to remember the half tank thing. I usually get more around 1/3 a tank. I have my doubts about the first one for the reasons already mentioned.

 

I have heard of the 1st two since I was in high science class but the last one I am not sure about.

Compared to the storage tanks, car gasoline tanks are not that big and the vapor would only be lost when you opened the tank.....which is minimal.

Sounds like it would be a good episode on Mythbusters.