Although the prices of gasoline and diesel have followed a similar trend, there are notable changes over time. From 1980 through 2004 the average annual diesel fuel price was below or nearly the same as regular gasoline, according to figures from the US Department of Energy (DOE).
From 2005 through 2018, the average annual price for diesel remained above that of regular gasoline and was 44 cents per gallon higher in 2018.
Retail prices for gasoline and diesel from 1980 to 2018 Note: Gasoline price is for unleaded regular gasoline. Prices were adjusted for inflation using the Consumer Price Index. Source: Energy Information Administration, Monthly Energy Review July 2019, Table 9.4.