Today, I filled up my gas tank. I have driven 99.5 miles farther than I am able to drive on an average tank in the same conditions.
A few weeks ago, I read this article about hypermiling, in which people go to insane lengths to squeeze the best possible gas mileage out of their cars. Wayne Gerdes, the guy featured in the article, gets 59 mpg in a Honda Accord. At one point in his daily commute, he exits a freeway going 50 around a 270-degree turn, shuts his engine off, and coasts for over a mile, carefully timing it so he hits two green lights. He keeps the windows up and the A/C off no matter what, wearing an ice vest from his day job at a nuclear power plant to keep cool. This is truly nuts.
But, as luck would have it, I had to fill up my gas tank on the same day that I read that article. So, I decided to make an effort to get the best gas mileage I could out of that tank. Today, my fuel light came on and I filled the tank again, so I’m reporting on the results of this experiment.
I drive a ’97 Honda Civic (standard transmission) to and from work every day, and almost never anywhere else. My daily commute is 20 miles round trip. I’ve been making the same exact commute for months, and I’ve kept track of my mileage with every tank, so I have a good historical data set to compare to.
On the average tank of gas (averaged over my last 20 tanks) driving this commute, I go for 271.14 miles, getting 28.0 miles per gallon. On this tank, I went for 370.7 miles, getting 35.88 miles per gallon, for an improvement of 99.56 miles and 7.88 miles/gallon. At the current gas price here ($2.49/gal), I figure I saved myself about $8.85 on this tank.
So, here’s what I did differently this time:
- Never accelerate uphill (fighting gravity)
- Look far ahead for lights. If they are red, just shift into neutral and coast. Don’t gun it to hit a green light.
- Take turns as fast as safely possible.
- In general, avoid using breaks if at all possible. Try to conserve momentum (okay, physics nerds, momentum is conserved whether I try to conserve it or not… you know what I mean!)
- Don’t speed. According to this Sierra Club interview with Wayne Gerdes, for every 5mph you drive over 60mph, you lose 7% of your gas mileage.
- Learn the details of my commute. For example, I now know how fast I need to be going to coast all the way into my driveway from a particular stop sign.
- There are some other good tips here.
Also, for the last few days, I turned off my engine if I was going to stop for more than 7 seconds. I have heard various figures for how long you need to be stopped before it makes sense to cut the engine, but Wayne Gerdes says 7 seconds, and I figure if anyone would know the optimal value, it’s him!
The bottom line is, this cost me nothing and had a big impact! I didn’t notice it taking me longer to get to work and back, and it was fun. For the next tank, I’m going to try increasing my tire pressure, tossing all the junk out of my car, going on a diet… okay, maybe not that. My goal is to get 400 miles on one tank.
UPDATE! Your mileage may vary! I can’t believe I didn’t think to say that when I was writing this.
Never accelerate uphill (fighting gravity)
Where are you, Kansas? Even Ohio has hills that have to be accelerated on. 🙂
Good post though, thank you.
Heheh, true. I work in Austin, which has its share of hills, but I just try to keep my speed constant going uphill, and only increase it when the road is flat or (better yet) going downhill.
Thanks for the link.