It is best to get it early in the morning as the gas is colder. It is also better to pump slower as less of the gas turns to fumes. http://www.bargainist.com/deals/2007/08/20-tips-to-save-money-on-gas/

Never fill up when there is a truck filling the underground tanks. When they fill the tanks it stirs up sediments and water that would normally settle to the bottom. If you fill at that time you will have some water and sediment in your fuel. I would expect that first thing in the morning would be the best time as few have filled thier cars and the fuel in the storage tanks has more time to sit and the water and contaminants to settle.

Tips For filling Your Gas Tank Only buy or fill up your car or truck 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. In slow mode 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 of the 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 worth for your money. One of the most important tips is to fill up when your gas tank is HALF FULL. 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.

Wednesday is the best day to get gas s that is the day they usually bring the prices down before the weekend goes up. And some places that still have gas wars choose Mondays for that, so be on the watch:-) We've got one in our big town that is about 20 cents less on Mondays, EVERY Monday.

Probably is best to get gas in the mornings.

The tanks are UNDERGROUND! Temperatures do not fluctuate below a standard depth. This is spam junk! Another proof that this is spam, why is there no collaborative evidence on various websites? If this is true then many different "experts" would be discussing it in their own words. Most of what is posted here is pasted directly from this spam mailer... I don't know what game they are playing, but read between the lines!

early morning so it does not vaporize as it is being put in your car use hydrogen fuel it is free and clean push the goverment to do something bmw has ha a vehicle since the 1970