Why gas prices don't come down fast enough

Last Friday, I was shocked to find 3.93 on a gas station's signage in Portland. But, I think that was some kind of a gimmick, because I noticed that most other stations close by were in the 4.13 to 4.20 range.
I wondered then when retail gas prices will come down, given that oil prices have retreated from the $140 levels, down to $125. Turns out that I did not have to wonder for long; here is the explanation from slate.com:

Oil prices have dropped to about $125 a barrel this week after reaching a peak of $147.27 earlier this month. Meanwhile, gas prices are still hovering around the $4 mark, down just a few cents from an all-time record average of $4.11 two weeks ago. Why does it seem like gas prices go up faster than they come down?

Because they do. Analyses of gasoline economics show that when the price of oil rises, it takes up to four weeks for gas station prices to catch up, with most of the increase taking place within the first two weeks. But when oil prices sink, it takes up to eight weeks for the savings to be passed along to consumers. The phenomenon is known as "asymmetric price adjustment" (PDF) or, more informally, "rockets and feathers."

A busy gas retailer will take delivery on a daily basis, so there's some pressure to pass along price hikes without too much delay. The stations can't raise prices too much, though, because consumers tend to be extra-vigilant about shopping for bargains when oil prices are on the rise. When the newspapers start reporting upwardly mobile barrel prices, drivers tend to comparison shop down to the penny. This keeps gas prices from rocketing even further.

The asymmetry that economists cite comes into play as soon as oil prices start to deflate. Freed from the constant reminders about rising fuel costs, drivers become less invested in looking for a bargain—and retailers don't have to worry as much about the competition. As a result, station owners can keep drivers happy by knocking just a few cents off the "old" price.

Got a question about today's news? Ask the Explainer.
Explainer thanks Severin Borenstein of the University of California-Berkeley, Matthew Lewis of Ohio State University, Mariano Tappata of the University of British Columbia, and Bart Wilson of Chapman University. Martha C. White is a freelance writer in New York.
Article URL: http://www.slate.com/id/2196273/