It’s a Science Experiment!

Inspired by a recent episode of Mythbusters, I’ve decided to undertake a small science experiment. I want see how many more miles I can get out of a full tank of gas simply by changing my driving habits. It’s a documented fact that the more aggressively you drive, the more gas you waste. As Kari, Grant and Tori showed on Mythbusters, driving stressed out or angry used up to as much as 1/3 more gasoline as when speed limits, traffic signs, etc. are obeyed. Now, I wouldn’t call myself an overly aggressive driver, but I do exceed posted speed limits from time to time, and if you ask my wife, she’ll gladly tell you that I take corners rather hard. So when I filled my tank on August 8th, I made a mental note that I was going to “go to my happy place” while driving around town. I would then compare my average milage during my experiment with what I’ve been getting over the last 10 fill-ups. Fortunately, I’ve been keeping track of my average miles per gallon since May for just such an occasion.

Using the data I’ve collected over the last ten weeks I’ve determined that I get an average of 258 miles to a single tank of gas which is about 21 miles per gallon. I rarely do highway driving so my around-town trips fall squarely at the low end of Honda’s 21-23 MPG rating for the Civic. It will be interesting to see how much, if any, I can increase my average miles per gallon simply by becoming a more responsible driver. Even if I don’t manage to get much more bang for my mileage buck, I can say without a doubt that I’ve actually enjoyed driving more these past few days than I usually do. Since I know I can’t speed, I plan my departure accordingly and give myself plenty of time to be places. This results in a more relaxed pace and a more enjoyable experience behind the wheel.

One unexpected side-effect of my experiment is that I can see how I must have been driving. When not on my bumper or passing me at dizzying speeds, other motorists have been generally cranky as I obey traffic signs and speed limits. It’s funny because I drive along and think “there but for the grace of God, go I”. As of today, my fuel gauge is reading half empty and my odometer says I’ve gone 153 miles. Pretty good, but as a friend pointed out to me, my car’s fuel tank is not symmetrical so the lower half of the tank probably holds less than the upper. This means we’ll have to wait for the experiment’s conclusion to see just how I did. I’ll be sure to do an update when I have the final results.

When this trial is over, I’ll probably go back to my lead-footed ways, but if I can get 10-20 more miles out of a tank of gas simply by obeying posted speed limits, I may take up permanent residence in my driving “happy place”. Stay tuned!

UPDATE: Well the results of my experiment are in. After running all the way past “E”, with no extra highway driving, I managed to get a full 278 miles out of my fill-up. That means that simply by obeying speed limits and curbing my aggressive driving, I managed to get a full 20 more miles from my car than normal. I increased my average miles per gallon from 21 to 23 which just about equaled an extra gallon of gas. Hooray for science!


  1. Great experiment! I’ve been thinking about trying it myself.

    * Scientist hat on*

    One thing bugs me about the graph is that you used miles per tank. Are you using the same number of gallons each tankful? My suggestion would be to plot your MPG over time instead of miles driven per tank. Unless you’re using the same number gallons each time, your results will be skewed.

    *Scientist hat off*

  2. Dave,

    Yeah, I didn’t bother to put the number of gallons for each fill up, but I have kept track of it. The total ranges from 12.0 gallons on the low side to 12.8 gallons on the high side with an average of 12.4 gallons for all. I think this isn’t enough of a variation to really mess up the results, but you’re the scientist, so you’ll have to tell me for sure 😉

  3. Actually, yes. Full warranty — even brakes, oil service, air filters etc. I haven’t paid for anything other than tire rotations. Even if I had to, she’s never broke down. 🙂

  4. What year/model Civic is it? I had a ’95 that I would run up to 450 highway miles on a tank. I used to keep pretty good track of my mileage & # gallons/fill-up and was always close to 40mpg (>90% highway miles). If you really want to track fuel economy, you should monitor mpg and not just raw miles.

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