The Wall Street Journal's Keith Johnson explains why gas prices haven't fall quite as quickly as oil prices in the past few weeks:

When prices are rising, everybody drives all over town to shave a cent off each gallon. Once oil and gas prices start to fall, people get thrilled by $3.88 gas, and fill up at the corner station. Since there’s less comparison shopping, gas stations don’t have to change prices as often….

The most effective way to make the retail gasoline market work better is to patronize more mom-and-pop gas stations, rather than huge branded chains. The more small, independent operators there are, the quicker gasoline prices are likely to fall in lockstep with oil, several researchers have found. That’s apparently because independent operators buy their gas at “rack rates” rather than from an upstream oil-and-gas giant.

--Bradford Plumer