Motivated by General Geekery

Only YOU can prevent gas waste

Written By: der5er - May• 17•06

With current gas prices, it seems everywhere I look, there’s an article about saving gas or getting better mileage. So, I thought I would jump on the bandwagon!
Seriously, I wanted to take a look at some tips that are proven, some tips that might actually work, since I’m about to incur a huge gas bill on my way to and from 5erFest.
I did some quick reading, opting for a Google search instead of all the local papers, since they are mostly repeating the same drivel they told us last year (and the year before that and the year before that….) that they probably gathered from a Google search. Of course, I found all of the usual tips:

  • Slow down
  • Don’t jack-rabbit start
  • Turn off the AC
  • Buy gas in the morning
  • etc…

Wait. Hold the phone. Buy gas in the morning? The reasoning goes, that you’re buying more dense gasoline when it’s cooler, so you’re actually getting more than a gallon when you buy a gallon. This one has always sounded fishy to me. It can’t expand that much…it just can’t. And I finally found someone who had the time and the brain power to figure out the savings. You’d think it would be huge with all of the gas tip lists spouting this tip. Well, it’s not. According to Chris, if the temperature of the tanks at the gas station varied by 18 degrees Fahrenheit, you might save 45 cents on a tank of gas. Of course, he’s being generous in his calculations and ignoring the fact that the temperature of the storage tanks changes hardly at all during a typical day (the tip ignores that, so why can’t he?). Here’s his conclusion about this tip:

The only possible way this ?tip? could be useful is if the station stores their gasoline above ground and you have a gas tank the size of a KC-10.


Most of the other tips I found had some ‘logic’ behind them that I found questionable. It all sounds good in theory, but has anyone actually proven it? Well, the nice folks over at have tested some:

  • Stop Driving like a maniac.

    This was the single most effictive means of saving gas. It all boils down to: Keep your foot out of it!.
    Accellerate like you’re in a Yugo, it could save you 37% in actual MPG!

  • Drive the speed limit

    Unless you’re going a very long distance, going 5-10mph over doesn’t save you much time anyway. Slow lane drivers, in Edmunds’ tests saved up to 14%!

  • Set the cruise, especially on flat roads.

    Turn it off on mountainous roads, as it may rev too high (and that’s bad). But in the flatlands, cruise could save you another 14%

  • Tire pressure…not really

    This one surprised me. I’ve always seen that as a tip and it always made sense. But, Edmunds drivers saw no real improvement in their tests. It does help with safety and reduces tire wear. So, do it anyway.

  • Turn Off the AC and roll down the windows to save gas.

    This one also always made sense. It turns out that modern cars have more efficient compressors, and rolling down the windows increases the car’s drag, eliminating any gains made by turning off the AC.

  • If you’re going to wait a long time, turn off the engine.

    I always thought this one was bunk, unless you were sitting for 15 minutes. Turns out I was wrong. If you’re going to stop for more than a minute-shut it down.

That’s it for the Edmunds tips. But I’ll throw one of my own in:

  • Coast down hill.

    If you’re in a manual transmission, that is. It wouldn’t be safe to try and shift an automatic into neutral while driving. But in a manual, it’s easy and safe. You’ll save gas because the engine isn’t operating under any load whatsoever.

Basically, there’s one tip that covers all of these. There’s one thing that can save you tons of gas. You need to change the nut behind the wheel. If you (the nut) change your driving style to be closer to that of an old lady in an 82 Buick, instead of Ricky Bobby (“Momma I’m goin fast!”), you’ll very likely save a lot of gas!

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  1. Chris says:

    Just because I’m a nosy bastard…wherever did you stumble across those calculations I ran? :)


  2. der5er says:

    I did a lot of Google searching for that one. The whole thing never sounded right to me, but I (not having an engineering degree) never knew how to do the calculations. I was actually looking for a table showing either the density or volume of gasoline at various temperatures. Then I searched “more gasoline at cooler temperature” out of desperation, but just hoping that there would be someone like you who had disproven the whole thing. I found you on page 2 of that search. Excellent work, by the way.

  3. Joel A says:

    Excellent post, Greg, and something quite different.

  4. der5er says:

    Valve Cover Installed!

    And Valve adjustment done! Actually, it still looks exactly like the picture from last night, so I’ve still got work to do. I used Shawn D’s ‘cam side’ valve adjustment procedure for checking the valve clearances. Interestingly, only one…

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