The idea that people curtail discretionary driving as an austerity measure should not be surprising. The media has sold Americans on the belief that we have a "love affair with the auto," implying that demand is inelastic. Obviously, except for adolescent nuts, that is bullshit. As people mature, driving becomes less an adventure, or leisure time activity, and more a time-consuming necessity.
I have been cutting down for years on driving so I can have more time(and money) to do other, more interesting things. I suspect I'm not alone.
Demand elasticity is an interesting topic. I think it is 90% when you factor in trucking use and so on - in the short run.
In the long run, it is surely more elastic as people have time to cancel vacations and soccer leagues and join car pools and change habits and so on. People want normally cancel an already scheduled vacation or activity when gas goes up, but they can damned sure not plan it for the next year.
What we may be seeing is the result of 3-4 years of folks slowly reconfiguring their lives to drive less.