I believe it is a combination of finding oil freaking everywhere (making barrels $40) and cars are 2x as efficient as they were even a few years ago. Just did a 13 hour road trip with my father in his Prius and we got 56 MPG!!! More people are driving these kinds of cars and if you go 2-3 times as far on the same fuel the demand just dropped 2-3 times. Gobs of TDI VW's out there getting 40 plus MPG.
