The national average price for on-highway diesel climbed to a record $6.285 a gallon this week, according to data the U.S. Energy Information Administration released September 15. The 32-cent weekly increase marks a 5.3% jump from the prior week and puts diesel roughly 68% higher than the same week last year.
Every region tracked by the agency saw prices rise. The East Coast recorded the largest weekly increase, climbing 41 cents to $6.158 a gallon, while the Midwest rose 30 cents to $6.250. The Gulf Coast remained the least expensive region at $6.027 despite a 27-cent increase, and the West Coast stayed the most expensive region nationally, moving up 26 cents to $7.250. Regular gasoline also rose, up 16 cents to a national average of $4.319 a gallon.
Analysts pointed to ongoing disruptions to oil and shipping traffic around the Strait of Hormuz as the primary driver behind the increase, with crude oil prices moving above $100 a barrel amid continued tension involving the United States and Iran. President Trump said this week that the United States remains open to negotiating with Iran, a shift from earlier remarks questioning whether an agreement would hold.
For trucking fleets, the increase adds further pressure to operating budgets already affected by rising maintenance costs. Industry research released this year found that carriers' average marginal cost per mile climbed 3.4% year over year in 2025, with maintenance expenses up 8.6% over the same period. Fuel surcharge mechanisms will offset part of the new fuel increase for carriers, but the pass-through is not immediate, leaving fleets to absorb a portion of the higher costs in the near term.
Source: Fleet Maintenance - https://www.fleetmaintenance.com/equipment/emissions-and-efficiency/news/55405775/diesel-prices-hit-record-high-as-strait-of-hormuz-disruptions-continue