FiveThirtyEight.com is awesome, my go to place for polling. I have a question for its proprietor, Nate Silver:
Will high gas prices would decrease turnout? And will rural and exurban (read: red) precincts would show the largest drop? If these rural voters are trying to save gas, they would also be more likely to be home when a pollster calls. Rural districts are also the part of the state where driving people to the polls and other Get Out The Vote is least efficient. Since most states are a 'plum pudding' mixture of red rural pudding and urban blue raisins, I would expect this to produce a small but significant 'blue shift' on election day.
Evidence against would be that people who drive a lot tend not to mind driving a lot - witness that among my friends in Chicago, gas prices are a frequent topic of conversation, but when I was in Colorado during $4 gas season, I didn't hear a word.