Box truck mpg: what each size gets, and what moves the number

Box truck mpg is one of the biggest numbers in your cost per mile, and one of the least reliable in a sales brochure. This guide collects every mpg figure the big rental fleets publish for their box trucks, sets them against the federal average for delivery trucks, explains what drags real mileage down, and shows what a couple of mpg is worth in a year of driving.

Published box truck mpg by size

The rental fleets list mileage estimates on their truck pages. Checked in October 2026:

SOURCE:U-Haul (page snapshot 2026-09-28, Internet Archive), OCT 2026;Budget Truck Rental, OCT 2026;Penske Truck Rental, OCT 2026;U-Haul (page snapshot 2026-09-28, Internet Archive), OCT 2026;Budget Truck Rental, OCT 2026;Penske Truck Rental, OCT 2026;U-Haul (page snapshot 2026-09-28, Internet Archive), OCT 2026;U-Haul (page snapshot 2026-09-28, Internet Archive), OCT 2026;U-Haul (page snapshot 2026-09-28, Internet Archive), OCT 2026;Budget Truck Rental, OCT 2026;Penske Truck Rental, OCT 2026

These are each fleet's own estimate, and Penske notes that mpg varies with load, terrain and driving. Treat them as best-case figures for a well-maintained truck in mixed driving.

Box truck mpg average: the federal figure is about 7

The Department of Energy's Alternative Fuels Data Center publishes average fuel economy by vehicle category from FHWA's Highway Statistics. It lists delivery trucks at about 7.2 mpg and class 8 trucks at about 6.3, in gasoline gallon equivalents.

SOURCE:U.S. DOE Alternative Fuels Data Center (from FHWA Highway Statistics 2024, VM-1), OCT 2026

As a national average built from highway data, it reflects trucks as they are actually driven rather than a best case. It sits below almost every rental estimate in the table, which is a fair warning about planning with brochure numbers. For box truck mileage on your own routes, the gap between the brochure and reality can be several mpg.

What moves your box truck gas mileage

• Weight. A full box burns more than an empty one. Running near payload costs mileage.
• Speed. Wind resistance rises fast with speed, and a box truck is a big flat face to the wind.
• Stops and idling. Every stop means accelerating the whole truck again; idling burns fuel at zero mpg.
• Terrain. Hills cost more than they give back.
• The box itself. A taller box has more frontal area; a roof fairing can help on highway runs. See box truck wind deflector.
• A reefer unit. A self-powered refrigeration unit burns its own fuel on top of the truck's.
• Tires and maintenance. Underinflated tires and a neglected engine cost mileage; see box truck tires.

What 2 mpg is worth

A small mpg difference turns into real money over a year. EXAMPLE, using the U.S. average gasoline price for the week of September 28, 2026 ($4.465 a gallon) and 50,000 miles a year:

EXAMPLE

SOURCE:U.S. EIA, Gasoline and Diesel Fuel Update, OCT 2026

Swap in your own miles, mpg and local price with the box truck cost per mile calculator or the trip fuel cost calculator.

How to measure your own mpg

1. Fill the tank to the automatic shutoff and reset the trip meter.
2. Drive your normal routes.
3. Refill at the same pump and note the gallons.
4. Miles divided by gallons is that tank's mpg.
5. Average several tanks, and track loaded and empty runs separately if your loads vary a lot.

Your own figure is the one to put in every cost-per-mile and rate calculation.

Diesel, gas and size

Diesel is not automatically better on mileage: Budget's diesel 26 footer and U-Haul's gasoline 26 footer list the same 8 to 10 mpg range, and diesel cost more per gallon in EIA's latest survey. Our diesel box truck guide works fuel cost per mile both ways. Weight matters too; see box truck weight, and for chassis classes, medium duty box truck. Sizes are on the box truck sizes chart.

SOURCE:U.S. DOE Alternative Fuels Data Center (from FHWA Highway Statistics 2024, VM-1), OCT 2026;U-Haul (page snapshot 2026-09-28, Internet Archive), OCT 2026;U-Haul (page snapshot 2026-09-28, Internet Archive), OCT 2026;U-Haul (page snapshot 2026-09-28, Internet Archive), OCT 2026;U-Haul (page snapshot 2026-09-28, Internet Archive), OCT 2026;U-Haul (page snapshot 2026-09-28, Internet Archive), OCT 2026;Budget Truck Rental, OCT 2026;Budget Truck Rental, OCT 2026;Budget Truck Rental, OCT 2026;Penske Truck Rental, OCT 2026;Penske Truck Rental, OCT 2026;Penske Truck Rental, OCT 2026;U.S. EIA, Gasoline and Diesel Fuel Update, OCT 2026

Questions box truck owners ask

Q-01What is the average mpg for a box truck?

The federal figure for delivery trucks, published by the Department of Energy from FHWA highway statistics, is about 7.2 mpg in gasoline gallon equivalents. Rental fleets advertise higher numbers for their own trucks, from 6 to 14 mpg depending on size and fuel. Your mileage depends on how and where the truck runs.

Q-02What mpg does a 26 ft box truck get?

The rental fleets we checked list 8 to 10 mpg for U-Haul's gasoline 26 footer and Budget's diesel 26 footer, and up to 13 mpg for Penske's diesel 22 to 26 ft trucks. Expect less when the box is full, the route is hilly or the truck idles a lot.

Q-03How do I calculate my box truck's mpg?

Fill the tank, reset the trip meter, drive normally, then fill again at the same pump. Divide the miles driven by the gallons it took to refill. Repeat over several tanks and loads to get a real average, and keep a separate figure for loaded and empty running if your loads vary.

Q-04Do diesel box trucks get better gas mileage?

Sometimes, but the published ranges overlap: Budget lists 8 to 10 mpg for its diesel 26 footer, the same as U-Haul's gasoline 26 footer. Diesel also costs more per gallon right now. Our diesel box truck guide works the cost per mile from current prices.