The surcharges have generated tens of millions of dollars in profit for railroad operator Union Pacific UNP.N and provided a modest earnings boost for UPS UPS.N, the companies said.
In the clearest publicly available example, Union Pacific collected $91.1 million more in fuel surcharge revenue than it paid for fuel during the second quarter, boosting profits by $83.2 million, or 14 cents per share.
Union Pacific's result far outpaced rivals, spurring concerns that fuel recovery charges are generating profit.
"Ultimately, fuel surcharges are a component of the overall cost we negotiate with customers and something they take into consideration when choosing Union Pacific and the service we provide," the company said in a statement.
U.S. railroads are the only transportation providers required to report fuel costs and surcharge revenue to federal regulators, offering a rare window into the impact of the charges since the Iran war began on February 28.
Fuel surcharges are designed to offset higher energy costs, but customers have long argued they can become disconnected from the actual cost of fuel and boost profits.
UPS and FedEx FDX.N have steadily increased the size of their fuel surcharges in recent years.
"The original part of the cost consideration almost seems to be lost in translation," said Mingshu Bates, chief analytics officer at invoice auditing firm AFS Logistics, referring to the growing surcharge rates.
When the average diesel price was $3.35 a gallon in August 2021, UPS added a fuel charge of about 9% to the base shipping rate for the everyday packages shipped to homes and businesses. That surcharge is 24.25% today for UPS and 23.75% for FedEx, according to an analysis by AFS Logistics.
UPS and FedEx, often described as a duopoly because of their dominance of the market, offer customers little room to push back because their fuel surcharges are broadly similar.
UPS Chief Financial Officer Brian Dykes said fuel surcharge collections had a "modest" net impact on consolidated operating profit in the latest quarter. Brie Carere, chief customer officer at FedEx, said they were "not a material driver of our adjusted operating income."
Neither company explained why the surcharge percentages have risen so sharply.
For contrast, the heavily regulated United States Postal Service imposed its first surcharge on April 26: 8% on most packages.