To build a fleet fuel budget, convert next year’s planned miles into gallons using each vehicle group’s real MPG, then price those gallons quarter by quarter against a current forecast. For 2027 that matters more than usual. EIA expects diesel to average $4.40 a gallon, but starting near $4.93 in the first quarter, while pump prices this September have run far above the forecast.
Data current as of September 23, 2026
The short version
- The forecast: EIA projects U.S. diesel at $4.40 a gallon and regular gasoline at $3.35 for 2027, down from $5.07 and $3.84 in 2026.
- The catch: on September 21, 2026, diesel averaged $6.53 nationally, $2.78 higher than a year earlier and well above the path EIA forecast in early September.
- Budget by quarter: EIA’s 2027 diesel forecast starts about 12% above its own annual average. Dividing an annual number by 12 underfunds the first half of the year.
- Plan three cases: the EIA forecast, a slower recovery, and today’s prices holding. Your contingency should cover the gap between your plan and the stress case.
- Track three variances: every month, split any overage into price, miles, and efficiency. Each one has a different fix.
Most fleet fuel budgets are built the same way: take last year’s fuel spend, add a percentage, divide by twelve. That approach held up fine when diesel moved a few cents a quarter. It did not hold up in 2026. In February, EIA expected regular gasoline to average $2.91 this year. By September, its estimate was $3.84. A 10% cushion on the February number would have been gone by spring.
We have helped fleets manage fuel spending since 1989, and the budgets that survive a year like this one share a few habits. They start from gallons instead of dollars, they price fuel by quarter, and they are built around a range of outcomes instead of one number. This guide walks through that method with the current forecast and gives you a free budget builder to run your own numbers.
Fuel prices change weekly and EIA revises its forecast monthly. The figures here are current as of September 23, 2026. Check the latest EIA weekly prices before you finalize your budget.
What will diesel and gas cost in 2027?
EIA’s September 2026 Short-Term Energy Outlook forecasts U.S. on-highway diesel at an average of $4.40 a gallon in 2027 and regular gasoline at $3.35. Both are expected to fall through the year as Middle East oil exports recover and inventories rebuild, so the first half of 2027 is forecast to cost noticeably more than the second.
| Fuel | Q1 2027 | Q2 2027 | Q3 2027 | Q4 2027 | 2027 average | 2026 average | 2025 average |
|---|---|---|---|---|---|---|---|
| On-highway diesel | $4.93 | $4.50 | $4.17 | $4.02 | $4.40 | $5.07 | $3.66 |
| Regular gasoline | $3.52 | $3.55 | $3.34 | $3.01 | $3.35 | $3.84 | $3.10 |
Source: EIA Short-Term Energy Outlook, September 2026, Table 2. 2026 includes EIA’s estimate for the remaining months.
Why the forecast and the pump don’t match right now
EIA finalized its September outlook on September 3. In the three weeks after that, the national diesel average climbed from $5.97 to $6.53, and regular gasoline rose from $4.16 to $4.48. EIA’s forecast assumes oil flows through the Strait of Hormuz gradually recover and that most shut-in Middle East production is restored in the second half of 2027. The agency itself says it expects more short-term volatility than its forecast shows, and that constrained flows beyond the end of 2026 would push diesel margins higher than its current numbers.
Diesel carries extra risk. EIA expects U.S. distillate inventories to stay below their five-year low through much of 2027, and fall is when distillate demand from harvest and heating season picks up. If your fleet runs mostly diesel, lean your planning toward the higher scenarios below.
The forecast itself keeps moving
A budget that depends on one forecast number is only as good as that month’s forecast. Here is how EIA’s own estimates shifted this year:
| Forecast | What EIA expected | Latest estimate |
|---|---|---|
| 2026 regular gasoline | $2.91 (February outlook) | $3.84 (September outlook) |
| 2026 diesel | $4.80 (April outlook) | $5.07 (September outlook) |
| 2027 diesel | $4.11 (April), $4.07 (August) | $4.40 (September outlook) |
That is not a knock on EIA. It is the best public forecast available, and it is the right starting point. It just means your budget needs a range around it and a scheduled time to update it.
Adjust for where your trucks actually fuel
National averages hide big regional gaps. On September 21, diesel averaged $6.14 in the Lower Atlantic states and $7.46 on the West Coast. For 2027, EIA forecasts regular gasoline at $2.89 on the Gulf Coast, $3.18 on the East Coast, and $4.48 on the West Coast. The simplest fix is to compare what your fleet actually paid per gallon in 2026 to the national average for the same months, then carry that difference into 2027. Your fuel card transaction history has the price paid on every fill-up, which makes this a ten-minute calculation.
How to build a fleet fuel budget, step by step
Start with gallons, not dollars. Group vehicles by fuel type and MPG, project each group’s 2027 miles, convert miles to gallons, price the gallons by quarter under several scenarios, add a contingency sized to the gap between scenarios, and then set spending controls and a monthly review so the budget gets managed instead of filed.
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Pull 12 months of gallons by vehicle
Dollars mix together price changes and usage changes, so they make a poor baseline in a year like 2026. Gallons tell you what your fleet actually burns. Export the last 12 months of transactions from your fuel card account and total gallons for each vehicle.
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Group vehicles by fuel type and MPG
A diesel box truck and a gas pickup don’t belong in the same line of a budget. They burn different fuels with different price paths. Group similar vehicles together, such as gas pickups and vans, diesel medium-duty trucks, and heavy diesel tractors. Mixed fleets should always budget gas and diesel separately.
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Project 2027 miles for each group
Start from this year’s miles and adjust for what you already know: vehicles you are adding or retiring, new contracts or service areas, and routes you are consolidating. This step is where operations and finance should agree, because miles are the part of the budget you control.
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Convert miles to gallons with real MPG
Divide projected miles by each group’s actual MPG from last year, not the window sticker. Idling, loads, and stop-and-go routes mean real-world MPG is almost always lower than rated MPG, and budgets built on rated MPG come up short every time.
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Price gallons by quarter
Apply the quarterly forecast for each fuel, plus your regional adjustment, to that quarter’s gallons. If your work is seasonal, shift miles into the busy quarters before pricing them. A landscaping fleet’s summer miles and a delivery fleet’s fourth-quarter peak land in quarters with different forecast prices.
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Run three scenarios
Price the same gallons under the EIA forecast, a slower recovery, and today’s prices holding. Choose one as your planning case and treat the gap to the stress case as your contingency.
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Subtract rebates and add fees
Per-gallon rebates lower your net cost, and per-card or monthly account fees raise it. Both belong in the budget as their own line items so you can see what your fuel program costs beyond the pump.
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Set controls and a monthly review
Turn the budget into card limits by driver or vehicle, then compare actual to budget every month using the variance method later in this guide. Re-forecast each quarter, or sooner if prices run well off your plan.
2027 fleet fuel budget builder
Add a row for each vehicle group. The example is an 11-vehicle service fleet. Prices use EIA’s September 2026 quarterly forecast and the September 21, 2026 weekly average.
| Vehicle group | Vehicles | Miles per vehicle per year | Real MPG | Fuel | Gallons per year | Remove |
|---|---|---|---|---|---|---|
| 13,333 | ||||||
| 10,000 |
Quarterly budget, EIA forecast
Even quarterly split: $22,196
Planning estimate only. Prices include taxes. Regional adjustment and rebates apply to every gallon. The slower recovery case is the midpoint of the EIA forecast and the September 21 price for each quarter.
With the example fleet of eight gas pickups and three diesel trucks, the same 290,000 miles cost about $88,800 under the EIA forecast, about $107,000 in a slower recovery, and about $125,000 if today’s prices hold. That $36,000 spread is the real planning problem for 2027, and no single number captures it.
Why you shouldn’t divide a fuel budget by 12
When prices are forecast to rise or fall during the year, an even monthly budget is wrong by design. EIA’s 2027 diesel forecast starts at $4.93 in the first quarter, 53 cents above the annual average, and ends at $4.02. A fleet that splits its annual budget evenly will run over in the first half and under in the second, even if every other assumption is right.
For the example fleet above, the first quarter needs about $1,860 more than an even quarterly split under the EIA forecast. That is not a spending problem. It is a timing problem, and it shows up in cash flow before it shows up in the annual total. Set monthly targets from the quarterly numbers, not from the annual total divided by twelve.
Seasonality compounds this. If most of your miles happen in summer, you burn more of your gallons in quarters EIA expects to be cheaper. If your peak is the fourth quarter, you get the lowest forecast prices of the year. Switch the builder’s seasonality setting and watch the quarterly bars move.
How much contingency should a fuel budget carry?
Size fuel contingency to the gap between your planning scenario and a realistic stress case, rather than a flat percentage. In 2026, a 10% buffer on February’s forecast would not have covered the actual run-up in gasoline, and diesel moved even more.
Here is a practical way to set it up:
- Pick a planning case you believe. For most diesel-heavy fleets right now, the slower recovery case is a sensible middle ground. Gas-heavy fleets with flexible routes can lean toward the EIA forecast.
- Hold the gap to the stress case as a separate reserve. Keep it out of the monthly operating budget so it requires a decision to spend, not a shrug.
- Write down your trigger. For example: if the EIA weekly average for your main fuel stays more than 10% above your planned price for four straight weeks, move the rest of the year to the next scenario and release reserve accordingly.
- Re-forecast on a calendar. EIA updates its outlook monthly. Refresh your plan at least once a quarter so the budget stays tied to current information.
What fuel costs per mile for a heavy truck
For Class 8 trucks, fuel averaged $0.482 per mile in 2025, about 21% of the record $2.336 total operating cost per mile, according to the American Transportation Research Institute. At EIA’s 2027 diesel forecast, the same truck would spend roughly $0.58 per mile on fuel, and about $0.86 if September 2026 prices held.
| Diesel price | Fuel cost per mile | Fuel per truck per year |
|---|---|---|
| $3.66 (2025 actual average) | $0.48 | $41,450 |
| $4.40 (EIA 2027 forecast) | $0.58 | $49,830 |
| $6.53 (Sept 21, 2026 weekly average) | $0.86 | $73,950 |
Derived from ATRI’s 2026 Analysis of the Operational Costs of Trucking: $0.482 per mile in fuel at a $3.66 average diesel price implies about 7.6 MPG, applied to ATRI’s average of 85,991 miles per truck. Across all types of fleets, fuel typically runs 15% to 30% of operating expense.
How to track your fuel budget every month
When fuel spending comes in over budget, split the overage into three parts: price (you paid more per gallon), miles (you drove more than planned), and efficiency (you burned more gallons per mile than planned). Price is mostly outside your control. Miles and efficiency are operational, and each one points to a different fix.
| Variance | How to calculate it | What usually fixes it |
|---|---|---|
| Price | (Actual price − budget price) × actual gallons | Station choice, rebates, re-forecasting. Largely a market effect. |
| Miles | (Actual miles − budget miles) ÷ budget MPG × budget price | Routing, job scheduling, and confirming whether extra miles came with extra revenue |
| Efficiency | (Actual gallons − actual miles ÷ budget MPG) × budget price | Idling, speed, maintenance, and checking for fuel that never went into the truck |
The three add up exactly to the difference between actual and budgeted spend. An efficiency variance that jumps without an obvious reason, like a heat wave or a new heavy-load route, is also the first place card misuse tends to show up.
Monthly fuel variance check
Where the difference came from
Most of the overage is price. Check where drivers are fueling and whether it is time to move the rest of the year to a higher scenario.
Actual MPG is 12.0. Negative amounts mean that part came in under budget.
Where fleets actually find fuel savings
You can’t control the price of diesel, but you can control how many gallons each mile takes and what drivers are allowed to buy. Driving behavior is the biggest lever. According to the Department of Energy, aggressive driving can cut fuel economy by roughly 15% to 30% at highway speeds and 10% to 40% in stop-and-go traffic.
| Lever | Typical impact | How to measure it |
|---|---|---|
| Smoother driving | Aggressive driving costs 15% to 30% on the highway and 10% to 40% in stop-and-go | Harsh braking and acceleration events from telematics |
| Speed | Each 5 mph over 50 mph lowers fuel economy by about 7% for light vehicles | Speed profiles by driver and route |
| Idling | A quarter to a half gallon per hour for light vehicles, more for larger engines | Idle hours per vehicle per week |
| Tire pressure and maintenance | Proper inflation adds about 0.6% on average. Fixing a serious engine problem can improve mileage far more. | MPG trend by vehicle after service |
| Purchase controls | Stops fuel and items that never go into company vehicles | Exception alerts and efficiency variance |
| Fuel grade limits | Blocks premium fuel in vehicles that don’t need it | Grade mix in card transactions |
Driving and maintenance figures are from the U.S. Department of Energy’s fueleconomy.gov, mainly for light-duty vehicles. Heavy trucks respond to the same habits, though the exact percentages differ.
A few costs are easy to leave out of a fuel budget: card and account fees, diesel exhaust fluid for newer diesels, fuel for equipment and generators bought on the same cards, and detours to reach an in-network station. If your current card only works at a limited network, the extra miles to get there come straight out of efficiency.
How Fuel Express helps you stick to a fuel budget
A budget only works if it gets enforced at the pump. Fuel Express fleet cards let you turn budget lines into spending limits by driver or vehicle, report every purchase in real time for your monthly review, and remove card fees from the equation entirely.
Limits that match your budget
Set daily, weekly, monthly, or per-purchase limits for each card, assigned to a driver, a vehicle, or both. Restrict cards to fuel only, or fuel plus maintenance, and limit fuel type so premium doesn’t end up in trucks that run on regular.
The data your monthly review needs
Every purchase posts to your online account with the gallons, fuel grade, station, driver, and time. That covers the price paid and gallons for your variance check, and the spending reports can be customized to how you budget.
No fees, plus rebates
There are no startup fees, no annual fees, and no per-card fees, so that line in your budget is zero. Eligible purchases earn per-gallon rebates based on volume, and your representative can give you a written rate to plug into the builder above.
Fuel on the route you planned
With acceptance at more than 320,000 fuel and maintenance locations, drivers fuel where they already are instead of detouring. Add Geotab telematics to track idling, speed, and MPG by vehicle, which are the numbers behind your efficiency variance.
If you’d like a quick number first, the calculator on our homepage shows what per-card fees are costing you now and sizes your fuel budget in a few clicks.
Fleet fuel budget FAQs
How do I build a fleet fuel budget?
Start with last year’s gallons by vehicle, group vehicles by fuel type and real MPG, project next year’s miles for each group, and convert miles to gallons. Price those gallons by quarter using a current forecast plus your regional price difference, run several price scenarios, subtract rebates, add fees, and set a contingency sized to the gap between your plan and a stress case.
What will diesel cost in 2027?
EIA’s September 2026 Short-Term Energy Outlook forecasts U.S. on-highway diesel at an average of $4.40 a gallon in 2027, starting around $4.93 in the first quarter and falling to about $4.02 by the fourth. On September 21, 2026, the weekly national average was $6.53, well above that forecast path.
What will gas cost in 2027?
EIA forecasts regular gasoline at an average of $3.35 a gallon in 2027, down from $3.84 in 2026. The quarterly forecast runs from about $3.52 in the first quarter to $3.01 in the fourth. The Gulf Coast is forecast to be cheapest at $2.89 and the West Coast most expensive at $4.48.
How much contingency should I add to a fuel budget?
Size it to the gap between your planning scenario and a realistic stress case rather than using a flat percentage. In 2026, EIA’s gasoline forecast rose from $2.91 in February to $3.84 by September, so a 10% buffer would not have been enough. Keep the reserve separate from the monthly operating budget and set a written trigger for releasing it.
What percentage of fleet operating costs is fuel?
Fuel is often 15% to 30% of a fleet’s operating expense. For heavy trucks, ATRI found fuel averaged $0.482 per mile in 2025, about 21% of the $2.336 total cost per mile. That share rises quickly when diesel prices climb.
Should I budget fuel monthly or quarterly?
Price the budget by quarter, because forecasts change by quarter, then set monthly targets from those quarterly figures and track actual spending monthly. Dividing an annual number by 12 will run over early in 2027 and under late in the year if prices follow EIA’s forecast.
How can I tell if I’m over budget because of prices or drivers?
Split the overage into three variances. Price variance is the difference in price per gallon times actual gallons. Miles variance is extra miles converted to gallons at budgeted MPG and price. Efficiency variance is the extra gallons burned beyond what your actual miles should have needed. Price is market-driven, while miles and efficiency point to routing, driving habits, maintenance, or misuse.
Can a fuel card help me stay on budget?
Yes. A fleet fuel card turns budget lines into limits at the pump. With Fuel Express, you can set daily, weekly, monthly, or per-purchase limits by driver or vehicle, restrict purchase and fuel types, and see every transaction in real time, which gives you the gallons and price data you need for a monthly variance review.
How often should I update my fuel budget?
At least once a quarter, and whenever prices run well off your plan. A simple trigger is when the EIA weekly average for your main fuel stays more than 10% away from your planned price for four straight weeks. EIA updates its Short-Term Energy Outlook every month.
Should gas and diesel vehicles be budgeted separately?
Yes. They follow different price paths and carry different risks. EIA expects U.S. diesel inventories to stay below their five-year low through much of 2027, which makes diesel more exposed to price spikes than gasoline. Mixed fleets should build separate lines for each fuel.
Put your 2027 fuel budget on a card that enforces it
A short application with no obligation. A Fuel Express representative will set up limits and reporting that match your budget, give you a written rebate rate, and have your controls in place before any card is used.
