From 1995 to 2012 the price of premium gasoline has been 25 to 30 cents (7-18%) higher than regular gasoline. After 2012, the price difference for premium gasoline began to rise more rapidly, reaching its highest level in 2017 at 50 cents per gallon. The price of midgrade gasoline is consistently between the regular and premium prices.
Note: Prices include taxes and have been adjusted for inflation using the Consumer Price Inflation Index.
Source: U.S. Energy Information Administration, "Petroleum and Other Liquids, Gasoline and Diesel Prices" website tabulation, accessed March 7, 2018.