Why the hybrid isn’t the answer

Pax Arcana

pontiacYou probably agree that the only thing more taxing than arguing over the environment is doing math.

Well hold onto your brain balls, bitches, because they’re about to get kicked with the hard feet of learning, Freakonomics-style.

Here’s the situation: Imagine your friend buys a Toyota Prius that gets 46 miles per gallon. You, on the other hand, drive a Toyota RAV 4 SUV that only gets 24 mpg. And you smell like salami, but that detail is not important. Your other friend rolls in a Land Rover that gets 14 mpg.

Now let’s say the RAV 4 driver switches to a Prius, and the Land Rover driver switches to a RAV 4. Who helps the environment the most?

You may be tempted to select the first friend, since the leap from 24 mpg to 46 mpg is greater than the leap from 14 mpg to 24 mpg. You’d be wrong, and the reason is that you’re as stupid as college kids:

Why does 10 m.p.g. matter more than 22? The reason is that the relationship between m.p.g and fuel savings is not linear but curvilinear. Ten m.p.g. at the bottom of the range matters a lot more than 22 m.p.g. higher up.

This is a hard concept for us to get our brains around. Richard B. Larrick and Jack B. Soll, reporting in Science (gated) found that only 1 percent of college students studied correctly perceived that an improvement from 14 to 24 m.p.g. saves considerably more fuel than an improvement from 24 to 46.

To give our brains a break, we might adopt a better way to look at fuel efficiency, aided by the manipulation of a mathematical tool in use in the Indus Valley almost 5,000 years ago — the unglamorous fraction.

The trick is one that even fourth-graders can master: invert the fraction. Let’s consider not miles per gallon but gallons per mile (or, to make the numbers prettier, gallons per hundred miles). By this metric, we get an unclouded picture: the Prius uses 2.17 gallons per hundred miles, the RAV4 uses 4.17, and the Range Rover uses 7.14.

Thanks to the mileage mirage, our efforts as a society may be somewhat misplaced. There are plenty of policy ideas afoot to get people into state-of-the-art, fuel-efficient cars, but a lot less interest in simply getting people out of the worst gas guzzlers into moderately more efficient alternatives, even within the same fuel-hungry class.

Luckily for all of us, my vehicle of choice actually adds more fossil fuels to the earth than it consumes. It’s a van I found unlocked and running behind the museum. I make sure to toss at least twenty fossils out the window for every gallon of gas.

Buy an S.U.V., Save the Planet [Freakonomics]


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