Have you heard the argument about hot gas? Gasoline loses some efficiency at hot temperatures, and also that gasoline tends to expand when it heats. This means that the higher the temperature of the gasoline at the pump, the less gasoline will be pumped into your tank. That sounds really bad, doesn't it! But, it's really not as bad as it seems at first glance, according to this article on The Oil Drum. So, which side is right? Well, that really depends. There is definitely a difference in the amount of gas that a pump will dispense into your tank based on the temperature of the fuel. So, the hotter the gas is, the less of it you will get. Filling up in Phoenix, you may get less gas in your tank than filling up in Alaska. Check out a pump the next time you add gas, there should be a label on there somewhere explaining that the pump was tested and certified using gas at a certain temperature. The closer the gas is to that temperature, the more accurate the pump will be. Gas is usually stored in underground containers, and a study indicates that the gas does not change temperature more than a couple of percentage points after being delivered, so the question is how hot was the gas when it was delivered, or how long has the gas been stored in the underground tank?
As you can probably tell, the only way to truly answer the "hot gas" question would be to measure the temperature of the gas as it enters your tank. Alternatively, and not very likely, the gas station retailers could all switch to pumps which are capable of monitoring the temperature of the gas being dispensed and compensate for it. This actually took place in Canada, where oil companies might have been losing out because the gas was too cold. Enough of this, and maybe we'll all just switch to electric cars!
[Source: TTAC, The Oil Drum and Oil Watchdog]