Wait a minute the TAXES and the cost of REFINEMENT is a PERCENTAGE per barrel and not a adjustable rate.
The only logical conclusion I can come up with is the depreciation of the dollar since the Fed is adding 85 Billion in NEW DOLLARS every month.
The cost to refine is not a fixed ratio to the cost of the barrel.
Neither is the marketing, taxes, distribution, etc...
Dollar depreciation affects crude oil and gasoline equally.
GASOLINE PUMP COMPONENTS HISTORY {Price}
http://www.eia.gov/petroleum/gasdiesel/gaspump_hist.cfm