UNINTENDED CONSEQUENCES. The U.S. Corporate Average Fuel Efficiency standards require that the mix of cars sold by automobile manufacturers meet a miles per gallon standard. Automakers respond to the standards by producing relatively more high-gas-mileage cars or relatively fewer low-gas-mileage cars. Why do you suppose station wagons are so hard to find? It's less about esthetics than it is about complying with the law. So why the oversized shopping cart called an SUV? Those are trucks, subject to the truck fleet fuel efficiency standards, and an unintended consequence of different rules for pickup trucks, intended at the time of the law to exempt farmers from hardships that others would be subject to.

The SUV has become a symbol in some circles of the wrong kind of conspicuous consumption, most recently in an Ariana Huffington anathema on them, now made public in something called the Detroit Project. A Small Victory is not impressed with the campaign. She makes the point that SUVs make carpooling a bit simpler. So would station wagons, but they're illegal. Result: people who want to transport larger families, or shopping cart loads of goods, end up buying SUVs instead, and consuming more gasoline for a trip of given length, and exposing themselves to a slightly greater risk of a rollover crash, while exposing others to a slightly greater risk in a collision. This last is not a trivial point. Several economists, most notably Brookings's Robert Crandall, have published research establishing a higher death rate as a consequence of the fuel efficiency standards. Meanwhile, people do not see the kind of price signal (more expensive fuel) that would encourage them to buy smaller cars, or to invent larger hybrid cars, although that work is in progress. That is not to say that more expensive petroleum products is desirable: that makes consumers poorer, and it encourages substitution toward coal or wood, whose combustion contributes to the Asian Brown Cloud. The life of an economist is challenging at times, but one never lacks for things to investigate.