Hypermiling and EPA vehicle efficiency estimates
Thanks for the welcome, Daniel!
I’m just getting settled into being back in Madison after a long road trip to Texas and back, during which my partner D was generous in driving the entire time, because I am a wimpy (and not particularly skilled) driver. We decided to drive partly to reduce travel costs, and partly to lower our carbon footprint.
To make the drive more interesting, my partner (during stretches of little or no traffic) decided to practice some hypermiling techniques. The idea of hypermiling is to use various driving practices, like pulsing and gliding in order to exceed the US EPA’s estimated fuel efficiency on one’s vehicles. Some of the techniques used by hypermilers are are relatively noncontroversial (like keeping your car maintained), while others (like drafting off trucks to avoid wind resistance) are much more controversial (and many hypermilers avoid them). According to D, some of these techniques are more “fun” (like thinking about ways to use hills to one’s advantage, and planning one’s routes to avoid using the brake as much).
So what’s this foray into hypermiling accomplished? In our blue ’05 Prius, we managed to get over 70mpg (EPA’s combined city/highway estimate is 46 mpg), which is still nowhere near the over 100mpg that some hypermiling marathoners have achieved. In his defense, D’s just starting. But he still might need more practice before being anywhere near competitive in the upcoming 2008 Hybridfest MPG Challenge.
One interesting thing is the relationship between hypermiling and official estimated fuel efficiencies for vehicles. If gas prices keep increasing, will more people adopt some of the more efficient driving techniques of hypermiling? After all, there’s already been studies that suggest that the amount of driving has decreased as a result of high gas prices. So what if the amount of driving not only goes down, but the actual driving is done with gas efficiency in mind? Is there a point at which the EPA must change its techniques for estimating vehicle efficiency to adapt to changing driver practices?
Update: As commenter Jon Garfunkel points out, there’s a lot more nuance to this.
The historically cheap price of gas in the U.S. (and vast size of the country, and commutes) hadn’t encouraged enough drivers to think about buying fuel efficient cars. So the Energy Tax Act of 1978 added the “gas guzzler tax” to push the disincentives up front to the purchase of a new car (strictly speaking, it’s assessed to the manufacturer, who duly passes it along in the total sticker price.) After all, even the most economically rational consumer can best weigh in the cost of gas today, not in the future, when they’ll be buying most of it.
There’s one twist: the gas guzzler tax is calculated based on the EPA mileage estimate. And the EPA in fact changed their formula a year ago. They changed it not to reflect the obscure hypermileage subculture*, but instead some more real world factors of like the A/C, quick acceleration, etc. And thus it increased the number of cars subject to the gas guzzler tax. If fellow liberals here are looking for administrative measures over the last eight years to celebrate, this could be one of them.