My wife Reanna was ambivalent about owning her first car, largely for reasons of environmental ethics. So when she got one she started reading about “hypermilers,” a group of people developing driving techniques to increase gas mileage in their vehicles.
I’ve been interested, of course–this is right up my alley–but have little time for reading these days. Here is the only hypermiling post I’ve read,which is quite good. Mr. Money Mustache, a financial blogger, monitors his miles per gallon, gallons per hour, and other information like engine temperature in real time while he drives. He uses a bunch of driving techniques, and averages 44 MPG in his Scion (rated at 27 MPG) in city driving. Some highlights from the article:
“‘If you have to brake, you’ve made a mistake’…. [P]retend [your brakes] are hooked up to a speaker on your dashboard which blares out my voice saying ‘MEEEEEEEHHHHHHHHHH!!!’ at you for the duration of your brake application….”
When you decide to drive 75 MPH, sing this song in your head: “I am Mister Fancy, I am in a hurry, my time is so valuable that I am wasting gas. Wasting gas, wasting gas, look out world I’m wasting gas. Tomorrow I will save some gas, but today I’m wasting gas”.
On the use of air conditioning: “Is it dollar-an-hour hot in here today, or not?”
Reanna started tracking her by-the-tank gas mileage right away, using Gas Cubby, so we have a record of the MPG for every tank of gas we’ve put in. Lately I’ve been driving it the most, so I decided on an experiment based on Saul Griffith’s (which I wrote a bit about and linked to here): I drove a full tank with an self-imposed speed limit of 60 MPH and then a tank at 55 MPH max. There are 65 and 60 MPH speed limits posted for parts of my normal commutes, so these new limits affected a significant amount of my driving–maybe a third? So to be clear, I drove normally for me (which does not include hypermiling techniques, for the most part) unless the posted limit was above my imposed new limit, when I would drive at that speed.
Hack display of 29 tanks in our 2-door Toyota Yaris. The X axis is MPG.
Sorry about the hack display, but I think it gets the point across. Each dot is a tank and bigger dots mean more tanks at that MPG. The tank with a 55 MPH speed limit was the least efficient driving, at 32.5 MPG and the tank with a 60 MPH speed limit was the most efficient, at 40.8 MPG. I really did not expect this. I expected 55 to be more efficient than 60 and I did not expect a limit of 60 to make much of a difference.
Some complications to consider: 1) It is winter right now, and we are not using air conditioning, while many of these tanks supplied energy for significant AC use. And colder engines are less efficient. 2) I was not perfect and exceeded by self-imposed speed limits accidentally, off and on. Also, I drove 10-15 minutes of my 55 MPH tank at posted speed limits of 60 and 65 because I had something time-sensitive to deal with while my mom was in the hospital. 3) Reanna drove the Yaris 25-30% of these tanks, and she is a congenitally slow driver, rarely exceeding 55 MPH.
And a note about the psychology of driving slower than a posted speed limit: I was surprised at how embarrassed and defensive I felt while driving slowly on the highway. It breaks a social norm that I didn’t often notice: Driving slower than a posted speed limit is deviant. You will drive as fast as you are allowed, if not faster. It reminded me of when, because of a back injury while a student at the University of Oregon, I started standing in the back of the class during lectures. I realized that no one stands during lectures or meetings, and it really sticks out when someone does, regardless of how harmful sitting is.
Nathen's Miraculous Escape 
February 8, 2014 at 3:53 pm
Makes me miss the Toyota Tercel that Bailey and I rode around the desert in a few years back. 45 MPG fully loaded with the AC on.
Kinda amazing what having a teeny tiny car will do.
February 9, 2014 at 9:46 am
When Frankie and I drove across the country to San Francisco (the LONG way, south to Florida, then the southern route all the way Arizona, then up through LA) we tracked our mileage the whole way and mostly drove the speed limit, which varied significantly from place to place. The best mileage we got was about 35 MPG (which is pretty great for a 96 Toyota Camry, stuffed to the gills with our heavy stuff) driving about 75 MPH through Texas in pretty hot weather on long straight roads. Our lowest MPG’s were on a few tanks driving down the East coast in colder weather staying at around 60-65 MPH.
I was always concerned that our data was off because I wasn’t sure how standardized of sensitive the automatic shutoff on the gas pumps were. I know you can almost always add at least another gallon after the first time the thing stops, and I was worried the the variation in how sensitive the pumps were about shutting off might make the data unreliable.
February 9, 2014 at 11:21 am
Yeah, I thought about that, too. I don’t top off the Yaris so I’ve never checked, but on my truck I could never get anything like a gallon in after the automatic shutoff. More like a pint.
April 29, 2014 at 9:56 am
Yea, I typed gallon, I think I meant dollar. There was a time when I always tried to get the pump to read double zeros after the dollar amount. I could reliably add a dollar and change (sometimes I’d miss the first time) to the gas tank after the shutoff. I’m using Fuelly to track mileage on my scooter now and my rules is that I just go with the first time it shuts off, but make sure to get as many drops that are left in the pump into the tank.