Wednesday, May 6, 2009

Understanding fuel efficiency

I just ran across this great post about fuel efficiency at the bottom of my briefcase. It came out of the New York Times Magazine that included their 8th Annual Year in Ideas.
In the short post, Richard Larrick makes the case that we should be changing the way we measure fuel economy. And it is so elegantly simple once you see it. Here is an excerpt.

But right now, he says, “as a national-policy question, the urgency is getting people out of the 14-m.p.g. vehicles.” And m.p.g. ratings aren’t the most useful prod, largely because the real significance of differences in m.p.g. is often counterintuitive. The jump from 10 to 20 m.p.g., for example, saves more gas than the one from 20 to 40 m.p.g. The move from 10 to 11 m.p.g. can save nearly as much as the leap from 33 to 50 m.p.g.

 Consider the much-mocked S.U.V. hybrids, which seem to offer only incremental gains. Someone who trades in an all-wheel-drive Cadillac Escalade (14 m.p.g.) for an Escalade hybrid (20 m.p.g.) would save 214 gallons of gasoline over the course of 10,000 miles. That’s about as much fuel as would be saved by two people currently driving 33-m.p.g. cars who switch to 50-m.p.g. hybrids, assuming everyone drives the same distance.

You can find the complete post on fuel efficiency here.