Why are diesel prices so much higher than regular gas?

Rising gas prices have garnered a lot of attention, but diesel prices have also sharply increased in recent weeks amid mounting military tensions with Iran.

The average price of a gallon of diesel fuel in the U.S. on Wednesday, Sept. 10, was $6.31, according to AAA. That's up from an average diesel price of $5.94 one week ago on Sept. 9, and $3.70 one year ago on Sept. 16, 2025, the group said. By comparison, the average price of a gallon of regular gas in the U.S. on Wednesday, Sept. 16, was $4.36.

Oil prices have also spiked amid continued escalation in the war between the United States and Iran. Futures for Brent crude oil, the international benchmark, reached about $106 per barrel on Wednesday, Sept. 16. Futures for November delivery of West Texas Intermediate, the U.S. benchmark, were trading at around $103 per barrel.

Patrick De Haan, Head of Petroleum Analysis at GasBuddy, said in post on X that gas and diesel prices are both expected to continue rising as the Iran war continues.

"We may set a new 2026 high for average gas prices by the weekend," he wrote. "Currently $4.371/gal and climbing, previous high $4.566/gal. diesel average…

Original source: https://www.usatoday.com/money/