The sticker price tells the tale when buying a car, but the variables are more numerous and far less predictable when budgeting for the costs of ownership — including the price of gas. Using data from the U.S. Department of Energy, Cheapism determined the average cost of a gallon of gas every year from 1940 through today, showing the price also in 2021 dollars. (Prices are for regular leaded through 1990, then for regular unleaded.) Despite constant ups and downs, significant swings in gas prices are relatively rare: The adjusted cost breaks the $4 barrier just four times, while staying around $2 for the vast majority of years. And major price fluctuations don’t always occur during times of upheaval and crisis.