Back before Memorial Day this year, gas prices appeared primed to churn ever higher and provide a hard hit to Americans’ wallets. At the start of May, the national average price of regular self-serve gasoline was $3.94 a gallon, according to AAA. But instead of climbing higher, gas prices eased to $3.60 a gallon in the height of summer–unexpected because normally that’s when we drive the most and a lot of refinery maintenance occurs, nudging up prices. Today the average per-gallon cost of gas is even lower, at $3.40 a gallon. It’s not cheap, but if you’re like me,...