One way to watch the future price of gasoline is thru First Fuel Bank. http://www.firstfuelbanks.com/V3/FuelPrices.aspx
It's in the St. Could area so not much good for me. The two amounts to compare are a "rolling account" and a "locked account". A "rolling account" is effectively a cash or prepaid "house debit card". Unleaded is currently $1.65.9 The "locked account" is cash or check prepay with the price locked in the future. For unleaded this is $2.39.9 This is basically seventy-two cents more for a hedged no expiration date future purchase of gas. Using a credit card for a "current price" purchase is a dime a gallon more than a "rolling account".
The dime a gallon more for credit cards seems like more of a promotion of the house cards than a real savings. Credit card companies charge 2% to 3% for gas payments so they came close to a dime when gas was pushing $4 per gallon.
Anyway, watch the left and right unleaded prices at http://www.firstfuelbanks.com/V3/FuelPrices.aspx to see future market trends.