According to EIA, the price spread between regular gasoline and premium, which has been increasing since 2000, accelerated over the past few years. It is now roughly 50 cents per gallon, more than double the spread in 2009. Part of the reason is an increase in demand and part of the reason is the cost to produce higher octane gasoline.
Premium gasoline as a percentage of the gasoline pool has increased from about 7% to almost 12%. While some increase in the use of premium can be attributed to motorists choosing a higher grade because of low gasoline prices, the major driver is the changes in engines that have been necessary to meet the fuel economy increases imposed by the Obama Administration.
CAFÉ regulations finalized in 2012 raised fuel economy for model years 2017-21 from 27.5 miles per gallon (mpg) to 40-41 mpg. Subsequently, the Obama EPA raised the standards to 54 mpg for model years 2022-25. The motivation for setting such stringent standards had little to do with improving air quality and everything to do with a goal of reducing CO2 emissions. To meet the tougher CAFE standards, automakers have had to implement a number of technological solutions, all of which have added at least $4000 to the average price of cars and more to the cost of trucks. In addition, to weight reduction, better aerodynamics, and engine and transmission efficiency, manufacturers have turned to producing turbocharged engines, which for many engines require the use of premium gasoline to avoid incomplete combustion.
At the same time, the changing slate of crude oils and environmental regulations have increased the cost of producing higher octane gasoline, 91-93 octane for premium versus 87-89 for regular. Between 2000 and 2012, refiners could rely primarily on blending ethanol, which has an octane rating of 115, to boost the octane rating of gasoline. Increasing volumes of light crude oils from imports and shale oil contain higher levels of parafifins which lead to lower gasoline octane levels and the hydro treating needed to meet the 2017 gasoline specifications also results in a loss of octane. As a result, refiners have had to turn to more expensive octane boosting processes.
Changes in CAFÉ standards and fuel specifications, ostensibly for environmental reasons, have raised the cost of light duty vehicles and the fuel that they must use without making a real contribution to air quality or climate change mitigation. They were driven by ideology and the increases in cost are simply a hidden tax on the use of gasoline and diesel, one that is highly regressive.