"How much of it is just a result of the bad economy? The unemployment rate has soared significantly since last summer; perhaps the only good thing about losing your job is that you no longer have to endure the drive to work.
To sort this out, I built a regression model that accounts for both gas prices and the unemployment rate in a given month and attempts to predict from this data how much the typical American will drive. The model also accounts for the gradual increase in driving over time, as well as the seasonality of driving levels, which are much higher during the summer than during the winter. (The results of the model are shown for the month of January in each year since 1980 in the graph above.)
The model predicts that given a somewhat higher unemployment rate but much lower gas prices, the lower gas prices should have won out: Americans should have driven slightly more in January 2009 than they had a year earlier. But instead, as we've described, they drove somewhat less. In fact, they drove about 8 percent less than the model predicted."