Tuesday, February 10, 2009

On gas mileage

There has been a lot of talk in the past few months on how Detroit has failed Americans by not producing smooth running, gas sipping, energy efficient cars. High gas mileage cars are a wonderful way to reduce emissions and fight global warming, or so it is said.

Well, not really, and the key is actual car use. Let's say I have been driving a gigantic General Fnords Gigantic SUV for the past few years. My budget for transportation is relatively fixed; I have $300 for gas a month, and I won't drive much over that. This pays a certain amount of miles traveled, that I will restrict to trips I really need when gas prices spike, and will cover maybe a couple of long weekend drives if the prices fall.

Now, let's say that I get tired of having to think twice before driving my monster-sized SUV to go out to buy some milk, so I get rid of it and buy an efficient, comfortable sedan from Japan. My new car gets roughtly twice the milleage, so I can drive much, much more and stay within budget - which means that I can drive more for the same price. This will probably translate that I will feel better about driving to Vermont once a month to the outlet stores, driving 10 miles to do groceries to use coupons at a specific store, and not even consider talking the bus to go to work as my car is oh-so-good in mileage.

The end result of a fleet with twice the mileage could well be a fleet that drives almost twice as much, clogging the roads with the same hopeless enthusiasm as before while feeling green and clean about it.

What is the better option? Well, a less popular one - one that makes people budget thinking on how much they drive. A higher gas tax is actually the one reliable way to make people reduce miles traveled, not just enjoy driving a bit more. This doesn't mean that Connecticut should raise this tax by itself -it something that makes more sense on a Federal level- but it should be on the table.


  1. MA just raised gas taxes. CT should, and use that revenue to balance the budget and fix crumbling bridges.

  2. Roger --

    I have a big problem with your post, concerning its treatment of the "rebound effect."

    The rebound effect from improved mpg's -- the extent to which drivers "invest" their monetary savings from higher fuel efficiency into driving more miles -- has been studied exhaustively. A few decades ago, IIRC, estimates may have ranged to 20% or a bit higher. In 2007, however, Kenneth Small and Kurt Van Dender published a sterling piece of research, "Fuel Efficiency and Motor Vehicle Travel: The Declining Rebound Effect," which indicated rather conclusively that, at present, the increased miles driven due to monetary savings from improved fuel efficiency are "consuming" only around 2% to 11% of the "otherwise" fuel savings (2% in the short run, 11% in the long run, as drivers buy more-efficient vehicles).

    Small and Van Dender are impeccable researchers. Their paper is well-known and broadly accepted. To casually suggest, in the face of it, as your post did, that doubling fuel economy could result in doubled VMT, is sophomoric.

    BTW, I agree w/ you that, as between a heftier gas tax and tougher mpg standards, I would choose the gas tax (I would note further that higher gas taxes would make it easier to enact tougher mpg standards!). But I also think we have a responsibility to scholarship and our community to put in a little more effort on research before we opine on such important subjects.

  3. Good paper. Thanks a lot for the link, actually.