U.S. Diesel Prices Soar Past $6 a Gallon to Record High Amid U.S.-Iran Conflict

Diesel prices in the U.S. soared past $6 a gallon Friday for the first time ever, and experts predict the costs will fall back on the consumer through steeper prices for everyday staples.

The U.S.-Iran war has severely disrupted the flow of oil, with the national average of diesel now $6.06 a gallon according to the American Automobile Association, up from $5.85 last week, as renewed hostilities persist. By comparison, the national average this time last year was around $3.71.

The spike in fuel prices has been driven by higher oil prices. The price of benchmark Brent crude oil, a key ingredient in diesel, spiked to $109 per barrel Thursday, amid widening regional instability. The active hostilities between Washington and Tehran are largely focused on the Strait of Hormuz, but the advances of Yemen’s Iran-backed Houthis pose fresh risks for the Bab el-Mandeb Strait, another key shipping route.

Continued disruption of the Red Sea chokepoint would be “devastating to the global supply of energy,” says Shuting Pomerleau, director of energy and environmental policy at the American Action Forum. A surge in Ukrainian strikes on Russian oil refineries have also significantly impacted production, she adds, bringing daily exports of diesel fuel down significantly compared to last year and therefore pushing up global prices.

President Donald Trump told an interviewer this week that he has no regrets over the Iran conflict. But the majority of Americans appear to disagree, with increased living costs, driven up by the war, proving to be a sticking point ahead of the November midterms. 64% of U.S. adults surveyed in late July said that the conflict with Iran has been “not worth fighting,” according to a poll conducted by the Associated Press. Furthermore, a Reuters/Ipsos survey of American adults conducted between Aug. 21-24 found that 74% of respondents felt their cost of living was moving on the wrong track.

The surge in diesel prices has sparked fresh concerns. While only around 3% of passenger cars on American roads use diesel, it’s relied upon for heavy transport, construction, farming, and military vehicles. Around 75% of all diesel consumption in the U.S. came from the transportation sector in 2025, according to the U.S. Energy Information Administration.

Pomerleau says that diesel's wider range of performance in terms of efficiency and safety makes it more desirable for heavy vehicles. “Diesel fuel has greater energy density than other liquid fuels, so it provides more useful energy per unit of volume,” she explains.

Estimating that prices in California could go beyond $8 per gallon, Patrick De Haan, head of petroleum analysis at GasBuddy, has warned: “Some pumps aren't even built to display what could come next.”

But with diesel a key component for several industries, American consumers can expect to experience steeper prices elsewhere too, experts say, and that’s on top of cost of living increases they’ve already experienced this year.

U.S. Department of Agriculture data suggests that energy, transport, and storage costs contribute to over 7% of total food costs. If these costs rise due to higher diesel prices, experts say perishable goods stand to be most impacted.

“The goods that need lots of refrigeration and are on long routes of transport that are perishable, so the vegetables, meat and dairy, those are more exposed to [diesel costs],” Bernhard Dalheimer, assistant professor in food economics at Purdue University, tells TIME.

Price increases could take a while to be seen at the grocery store, though, as Dalheimer notes shifts in costs can travel “very slowly through the food pipeline.” But when they do trickle down, the increase is more likely to impact lower income families. “These could be small price changes, but people with lower incomes spend a higher proportion of their income on food,” he explains.

“Their margins are being squeezed quite dramatically right now. They're under a lot of pressure,” says Dalheimer, explaining that producers have little alternatives than to take on the higher energy costs. “Combine harvesters, tractors and heavy transport trucks, they all need lots of energy and there isn’t an alternative to diesel,” he explains.

“Farmers need to move all of their products from the farm to the grocery store shelves, so they have to pay for that extra cost, no matter how much that is,” adds Pomerleau, stressing that farmers still need to use diesel for agricultural machinery and transporting produce, regardless of fuel costs.

Approximately 76% of the 17 million commercial vehicles in the U.S. are powered by diesel engines, according to the Engine Technology Forum. As such, a lot of mail and shipping couriers have already passed on rising costs this year to consumers.

In March, the U.S. Postal Service sought a 8% charge on certain domestic products, citing increasing transportation costs, which came into effect in April up until January next year.

Amazon also introduced a 3.5% fuel and logistics surcharge on U.S. and Canada-based third-party sellers earlier this year, in response to rising fuel costs following the onset of the Iran war.

"Heating oil and diesel are very similar,” says Pomerleau. "Winter's coming. Some regions in the United States, for example, New England. If you look at the state of Massachusetts and Maine, a lot of households do use heating oil to heat their houses in the winter, and heating oil also comes from crude."