Diesel Prices Are Rising: Can You Separate Fuel Exposure From Freight Inefficiency?

When diesel rises by more than 30 cents in one week, how much should your company’s freight expense increase? For many CFOs, the honest answer is: “We will know when the invoices arrive.” That is a visibility problem.

The U.S. Energy Information Administration reported that the national average price of on-highway diesel reached $6.285 per gallon on September 14, 2026. That represented a weekly increase of $0.318 and a year-over-year increase of $2.546 per gallon.

Regional differences were also substantial. The Gulf Coast average was $6.027 per gallon, while the West Coast average was $7.250. California’s reported average exceeded $8 per gallon.

These figures do not automatically tell a consumer packaged goods company what it will pay. They do, however, create an urgent financial question.

Fuel Is a Market Cost, but Its Impact Is Company-Specific

A manufacturer cannot control the national diesel market. It cannot eliminate the influence of crude-oil prices, refinery conditions, inventories, taxes, regional supply constraints or international distillate demand.

It can understand how those outside conditions flow through its transportation agreements and operating decisions.

The amount a shipper ultimately pays can depend on:

• The diesel index named in each carrier agreement
• The base fuel price used in the surcharge formula
• The assumed fuel economy or mileage calculation
• The geographic index applied to the shipment
• The frequency with which the surcharge resets
• Whether the charge is calculated per mile or as a percentage
• Whether billed mileage matches the approved methodology
• The number of shipments and partially utilized loads

This is why two CPG companies facing the same diesel market may experience very different changes in freight expense.

One company may have disciplined shipment consolidation, clearly defined surcharge provisions and strong trailer utilization. Another may move similar sales volume through frequent partial loads, inconsistent order patterns and carrier agreements that are difficult to audit.

Begin With the Contract, Not the Invoice Total

A fuel surcharge should be evaluated against the governing carrier agreement or approved rate schedule.

The finance team needs to know which index is being used, what base fuel level applies and how changes in that index convert into charges. A national average should not be assumed if the agreement specifies a regional index or another source.

Timing also matters. A carrier may update its surcharge weekly, but the effective date and shipment-date treatment need to match the agreement. A sudden market movement can create timing differences between the current index, the carrier invoice and the company’s internal accrual.

Questions to Ask About Each Agreement

• Is the fuel-index source explicitly defined?
• Does the billed index match the correct week?
• Is the base fuel price documented?
• Is the fuel-efficiency assumption documented?
• Are mileage and rounding rules clear?
• Are minimum-charge and accessorial interactions understood?
• Can accounts payable independently reproduce the calculation?

If the calculation cannot be reproduced independently, the company has an invoice record—but it does not yet have reliable fuel-cost visibility.

Translate Diesel Movement Into Financial Exposure

Executive reporting should translate a change in the fuel index into estimated dollar exposure before the month closes.

Consider the following simplified hypothetical example.

This is an illustration—not a market benchmark, customer result or financial forecast. Actual surcharge formulas, effective dates, mileage, contracts, equipment and shipment volumes vary.

The calculation also does not establish what a carrier actually pays for fuel. Its purpose is to demonstrate the financial value of sensitivity modeling.

A CFO Should Be Able to Ask:

• What is the estimated effect of every $0.10 diesel movement?
• How much exposure sits with each carrier and geographic region?
• Which customer channels have the greatest fuel sensitivity?
• What portion of the monthly variance came from the index?
• What portion came from shipment volume, mix or execution?

Do Not Let Fuel Hide Controllable Freight Costs

During a sharp fuel increase, it is easy to classify the entire transportation variance as market-driven. That can conceal operational costs that remain controllable.

Connect Freight Expense to Delivered Margin

Aggregate freight expense is necessary for financial reporting, but it is not sufficient for commercial decision-making.

A CPG company may grow revenue while weakening delivered economics if the new volume comes with smaller orders, longer delivery distances, expensive appointment requirements or low-density products.

This becomes especially important when other input costs are also under pressure. The FAO Food Price Index rose 1.9% in August 2026, with all five commodity groups increasing.

That global index does not represent the exact ingredient costs of a particular U.S. manufacturer. It does illustrate why companies may need to manage commodity and transportation pressures simultaneously.

Freight Metrics Worth Reviewing

• Freight cost per case
• Freight cost per pallet
• Freight cost per order
• Freight cost per pound or hundredweight, where appropriate
• Freight as a percentage of net sales
• Delivered margin by customer, product and channel
• Fuel surcharge as a percentage of transportation expense

No single metric tells the full story. Cost per case may rise because the network became less efficient, the product mix changed or the company intentionally entered a more distant but strategically valuable market.

Effective reporting combines accurate measurements with the business context behind them.

Where AI-Assisted Freight Analysis Can Help

Freight information is often spread across carrier invoices, transportation systems, ERP records, warehouse data, customer orders, contracts and spreadsheets.

AI-assisted tools may help extract, organize and classify that information. Potential applications include:

• Separating linehaul, fuel and accessorial charges
• Normalizing carrier names and charge descriptions
• Matching invoices to shipments and approved rate records
• Flagging unexpected changes for human review
• Grouping costs by lane, customer, product or facility
• Producing variance summaries for finance and operations

Extracted invoice data still needs to be checked. A flagged charge is not automatically an overcharge, and a proposed load combination may not be operationally possible.

Weight, cube, temperature, handling, equipment, appointments, transit requirements, product compatibility and customer service constraints still matter. Carrier contracts and original source records remain authoritative.

AI is most useful as an analytical assistant that accelerates review and focuses expert attention—not as an unsupported promise of autonomous savings.

A Practical Executive Checklist

The objective is not to explain every cost increase as an external market event. It is to establish a defensible bridge between diesel conditions, carrier charges, operating activity and financial results.

Turn Freight Data Into Financial Intelligence

Fuel volatility is unavoidable. Freight opacity is not.

A CPG company with reliable shipment, invoice and contract information can estimate exposure earlier, explain variances more accurately and focus operational attention where it may have the greatest value.

The most useful executive question is not simply, “Why did freight go up?”

The numerical example in this article is hypothetical and is provided only to demonstrate freight-cost sensitivity modeling. Actual fuel-surcharge formulas, carrier agreements, mileage calculations, equipment requirements and shipment conditions vary. Operational and contractual findings should be reviewed by qualified freight professionals before implementation.