When adjusted to constant 2021 dollars, the average annual price difference between regular and premium gasoline remained between 27 and 33 cents per gallon from 1995 to 2012. Following that period, the average price difference began to increase sharply, peaking at 70 cents per gallon in 2020 and dropping slightly to 68 cents per gallon by 2021. The average price difference between midgrade and regular gasoline followed a similar trend but the difference in price was much less, peaking at 27 cents per gallon in 2019.
Notes: Octane requirements may vary by altitude.
- Premium gasoline - Gasoline having an antiknock index, i.e., octane rating, greater than 90.
- Midgrade gasoline - Gasoline having an antiknock index greater than or equal to 88 and less than or equal to 90.
- Regular gasoline - Gasoline having an antiknock index greater than or equal to 85 and less than 88.
Source: U.S. Energy Information Administration, U.S. Gasoline and Diesel Retail Prices, queried on October 24, 2022.