Diesel Spiked $1.17 in Eight Days. Your Fuel Surcharge Is Still Catching Up to Last Month.

Diesel moved $1.17 in eight days. Your fuel surcharge is still catching up to where prices were before that happened — and by the time it does, prices will have moved again. That gap between pump reality and benchmark fiction comes straight out of your fuel card.

This isn't bad luck. It's how the system was designed.

The Iran War Made Diesel a Different Animal Than Gasoline

The Strait closure pulled roughly 14 million barrels per day off the global market — about 14% of projected 2026 global supply, according to analysis from the Bipartisan Policy Center.

That number matters beyond the headline. Middle Eastern crude yields more diesel and jet fuel per barrel than the domestic alternatives U.S. refiners are now scrambling to substitute. You can't close that gap by drilling more wells in Texas. The chemistry doesn't work that way.

The result: U.S. diesel prices are up 58% year-over-year, compared with 42% for gasoline. This isn't one spike hitting every pump equally. Diesel is absorbing a disproportionate share of the war's energy shock. The Bipartisan Policy Center makes clear that even after fighting stops, restarting production and refining will take months. Anyone banking on a ceasefire to fix their fuel costs is going to wait a long time.

The Surcharge Lag Is the Real Wound

At the start of March, diesel was under $4 a gallon nationally. Then it surged 96 cents on March 9, followed by another 21 cents on March 16.

Your FSC formula wasn't watching any of that in real time. Fuel surcharges are pegged to national EIA weekly averages — a number that by definition reflects what diesel cost several days ago, not what you paid Monday morning before a 600-mile run.

Dean Croke, Principal Analyst at DAT iQ, described exactly how this plays out:

"The EIA weekly average has finally caught up to where today's pump prices are, which means the fuel surcharge will start to reflect the retail surge we've seen."

Read that carefully. "Finally caught up." He's confirming what every owner-operator already knows: the benchmark trails the pump. The catch-up eventually happens. The weeks between the spike and the catch-up — that's your money, not the broker's.

On a 10,000-mile month at a 55-cent-per-gallon gap, with a truck averaging 6 miles per gallon, that's roughly $917 in unrecovered fuel cost. Per month. Gone.

Brokers Baked the FSC Into the Rate — and That's Your Problem Now

When a broker quotes you an all-in rate, they've folded the fuel surcharge into a single number. That structure is convenient for them and catastrophic for you in a spike.

When diesel drops, all-in rates drop with it. When diesel climbs, the all-in rate doesn't always follow — because the broker isn't eating the difference. You are.

Some contracts make it worse. Surcharge formulas that assume a base diesel price of $1.25 a gallon were fiction before March. At $5-plus diesel, those assumptions are a direct transfer of wealth from your fuel card to the broker's margin. If the contract caps the surcharge at $0.45 per mile, you're still short regardless of what the pump says.

None of this is accidental. Brokers wrote these contracts for a market that no longer exists. They have not been calling you to offer corrections.

Spot Carriers Are Bleeding. Contract Carriers Have a Floor.

Jason Miller, the Eli Broad Endowed Professor of Supply Chain Management at Michigan State University, put it directly: trucking companies exposed to the spot market are "especially vulnerable to financial challenges from rising diesel prices, compared to firms with fuel surcharges that insulate risks."

Contract carriers have a floor, however imperfect. The fuel surcharge formula might lag and it might cap out below where you need it, but there's a mechanism. Spot carriers don't even have that. Load prices on the spot market are not rising fast enough to cover elevated fuel costs. You're pricing freight in a market that's moving slower than your fuel bill.

If you're running primarily spot, the question isn't whether this is hurting you. It's whether you know exactly how much.

Don't Wait for a Ceasefire

The first major leg of this spike hit in March. The second leg is happening now. Anyone who absorbed the March surge and waited for relief just got hit again with the same logic — the market moved, the benchmark lagged, and the driver's fuel card covered the gap.

The Bipartisan Policy Center's assessment of EIA forecasts is unambiguous: even in a post-conflict scenario, restarting production and refining capacity takes months. The structural diesel deficit created by the loss of Middle Eastern crude doesn't flip off like a light switch.

Pull your broker contracts this week. Find the FSC cap language. Look for the base diesel price assumption — if it's anywhere near $1.25, that clause is costing you money every single day. Calculate your actual per-mile fuel cost at current pump prices and compare it to what your fuel surcharge actually recovers.

What you paid at the pump minus what the surcharge recovered equals what you donated to the freight chain. Run that number. Then decide whether you want to keep donating.

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Brokers aren't going to call you with a correction. The math that doesn't work stays your problem until you make it theirs.

Photo by Romain Gal on Unsplash