After several weeks of falling oil prices, gasoline is finally following suit. The Energy's Department's latest weekly survey shows that the average price of self-serve regular in L.A. is 2.556 a gallon, down from $2.620 the week before. But there's a lot of catching up to do. Crude oil in NY closed today at $51.21 a barrel, a 19-minth low. Oil prices have plunged 16 percent this year alone and 35 percent from the record-high in July. So why isn't gas a lot cheaper? Good question.