From the department of obvious stuff: blogger CalculatedRisk demonstrates that when oil prices (in black) soar and recession (in blue) hits, vehicle travel (in red) plummets.
Although correlation doesn’t prove causation, I think it’s completely fair to say that the huge dip in vehicle travel (the big red V in 2008 and 2009) was caused by a combination of high gas prices and a collapsing economy—showing, among other things, that people really do pay attention to costs when they decide whether to hop in the car.
A similar trend is the price of large SUV’s during the periods of increase gas prices. The market for used SUV’s dropped $4000 plus during that same time period. dealers could not give them away.