I got the first part of that e-mail (the tips on getting more gas for your money) a while back, before even Snopes had addressed it, and wrote a quick response to the guy that sent it to me. Snopes covers it now, if you'd rather read their take on it ( <http://www.snopes.com/inboxer/household/gastips.asp> http://www.snopes.com/inboxer/household/gastips.asp), but I'll still copy what I wrote, too. Anyway, the main point is, even for some of those tips that may be technically true, the cost savings are pretty insignificant. Oh, and as far as the second half of the e-mail, regarding oil imports from Middle Eastern countries, Snopes has addressed that, too (http://www.snopes.com/politics/gasoline/saudigas.asp). Most of the information is either outdated or flat out wrong.
Hmm, at first I was thinking it was all technically true, just not very significant. The more I think about it, the more insignificant the effects seem. The part about a gallon not being a gallon seemed a bit silly to me. I realize what the author was trying to get at - that the warmer it is, the less dense the gas is, so the less of it you're getting by mass, but their explanation was pretty bad. Plus, doesn't the fact that the tanks are buried underground mean that temperature stays a lot more constant than if they were above ground? I wonder just how much the temperature fluctuates during a day. I'd be willing to bet that it's pretty insignificant. The part about gas evaporating if your tank's almost empty seems pretty silly, too. First of all, unless your tank was completely empty (like newly installed, never had a drop of gas in - not likely if you actually drove your car to the station), your tank's already full of gasoline vapor. It's probably already at its max partial pressure. More gasoline won't evaporate unless you get rid of that vapor. But, even assuming that your tank was completely open to the atmosphere, gasoline doesn't evaporate _that_ fast. I can think of plenty of projects where I've poured gas into a coffee can for cleaning a part or something, and I don't see the gas evaporating in front of my eyes. It usually doesn't take me more than a few minutes to fill up my tank, so I can't imagine that a significant amount of gas would evaporate in that time. I wonder about the part on pumping gas faster making it evaporate more, too. Same problem as above. Your gasoline may be slightly warmer because there's more work being done to it to get it to pump faster, but you've still got the problem that you're pumping it into a mostly closed container that's already going to be full of gasoline vapor. Plus, it's not like gas stations have terribly fast pumps - the pump at the airport I used to work at would put out a gallon every couple seconds or so (it was 8 years ago that I worked there, so I don't remember exactly). Probably the best advice to get the most mileage for your money is to adjust your driving habits, and not accelerate hard. I'd bet that would make your gas go a lot farther than only filling up on the slow setting on cold days. The part about the tanker stirring up sediment seems like good advice, though. -Jeff Lewis
