By Luis Lopez, AI transportation consultant, CEO of Go Hub.io Holdings Corp and subsidiaries, and host of the Freight Guru Podcast
Fuel is one of the largest operating costs for any truck fleet, and it is one of the few that a fleet can influence every day. The price per gallon is set by the market. How many miles a truck gets out of each gallon depends heavily on decisions the fleet and its drivers make: how fast trucks run, how long they idle, how they are maintained, and how loads and routes are planned.
This article walks through the main factors that drive truck fuel efficiency and how to measure progress honestly.
Speed: The Biggest Lever Most Fleets Control
Aerodynamic drag rises sharply as speed increases. At highway speeds, a large share of the engine’s work goes into pushing air out of the way. Running a few miles per hour slower can make a meaningful difference in fuel use over a full week of driving.
Fleets manage speed in a few ways:
- Governed road speed: setting a maximum speed in the engine control module.
- Cruise control settings: encouraging cruise use on open highway, where it usually holds a steadier speed than a driver’s foot.
- Predictive cruise features: some systems use terrain data to manage speed over hills rather than holding a fixed speed.
Speed policy has trade-offs. Slower speeds reduce fuel use but add time to each trip, which affects hours-of-service planning and delivery windows. A fleet that lowers governed speed should check that its schedules still work within the 11-hour driving limit and 14-hour on-duty window drivers operate under.
Idling: Burning Fuel While Going Nowhere
An idling truck burns fuel without moving freight. Drivers idle for real reasons: heat or air conditioning during rest periods, keeping the cab comfortable while waiting at a dock, keeping the engine warm in cold weather, and powering electronics.
Reducing idle time starts with understanding why it happens. Common sources include:
- Overnight rest periods in the sleeper berth.
- Long waits at shipper and receiver docks.
- Waiting at ports, rail ramps and fuel stops.
- Habit, where the engine simply stays running.
Auxiliary power units and other options
An auxiliary power unit, or APU, provides heat, cooling and electrical power to the cab without running the main engine. Some are small diesel engines; others are battery-based systems that store power while the truck is driving. Fuel-operated cab heaters, battery-powered air conditioning, and shore power at equipped truck stops are other options.
Each option has a cost, weight and maintenance profile. The right choice depends on the climate where trucks operate and how drivers use their rest periods. Many states and localities also have anti-idling rules, so fleets should check where their trucks spend time.
Dock waiting time is a shared problem. Shippers and carriers who work on appointment discipline reduce both idling and wasted hours. Our guide on how to reduce truck detention time covers that side of the issue.
Aerodynamics: Shaping the Truck and Trailer
Because drag matters so much at highway speed, the shape of the tractor and trailer has a direct effect on fuel use. Common aerodynamic devices include:
- Roof fairings and cab extenders: smooth airflow from the tractor to the trailer.
- Trailer side skirts: reduce turbulent air under the trailer.
- Trailer tails: fold-out panels at the rear that reduce the low-pressure area behind the trailer.
- Gap reducers: narrow the space between the tractor and trailer.
- Wheel covers and mud flap designs: small gains that add up on long-haul routes.
Aerodynamic devices deliver the most benefit on long highway runs at steady speed. On short, stop-and-go urban routes, the gains are smaller, and some devices can be damaged at docks or tight yards. Match the equipment to the duty cycle.
Tires and Tire Pressure
Rolling resistance is the energy lost as tires flex against the road. Underinflated tires flex more, wear faster and waste fuel. They also run hotter, which raises the risk of failure.
Practical tire steps include:
- Checking pressure regularly with a calibrated gauge, not by appearance.
- Using tire pressure monitoring or automatic inflation systems on trailers.
- Choosing tires designed for low rolling resistance where they suit the application.
- Keeping alignment in specification, since misaligned axles drag tires sideways.
Route and Load Planning
Fuel efficiency is not only about the truck. The work assigned to it matters just as much.
- Route choice: fewer stops, less congestion and gentler grades reduce fuel use, even when the distance is similar.
- Empty miles: every mile driven without freight burns fuel without revenue. Better backhaul planning reduces it.
- Load weight: heavier loads use more fuel, which is unavoidable, but poorly distributed loads can also affect handling and tire wear.
- Trip timing: avoiding peak traffic hours reduces stop-and-go driving.
Driver Behavior and Coaching
Two drivers in identical trucks on the same route can get noticeably different results. The difference comes from habits such as:
- Hard acceleration and late, heavy braking.
- Shifting practices on manual transmissions.
- Anticipating traffic and coasting toward stops.
- Use of cruise control on open highway.
- Idle time during breaks and waits.
Coaching works best when it is fair and specific. Compare drivers on similar routes and equipment, explain what the data shows, and recognize improvement. As an AI transportation consultant, the first thing I look at in a fuel program is whether drivers trust the numbers. If the comparisons ignore route, terrain or load differences, drivers stop listening. The approach in our article on AI driver safety scoring and coaching applies to fuel coaching as well.
Maintenance
A poorly maintained engine wastes fuel. Clogged air filters, injector problems, dragging brakes, worn bearings and exhaust aftertreatment issues can all raise fuel consumption. Often the first sign of a mechanical problem is a gradual drop in MPG for one truck.
Fleets that track fuel use by unit can spot these trends early. Predictive tools that combine engine fault codes, fuel data and inspection history help maintenance teams act before a small problem becomes a breakdown. Our guide on AI predictive maintenance for truck fleets covers how that works.
Measuring MPG Correctly
Many fuel programs fail because the measurement is wrong. Common mistakes include:
- Using dashboard MPG alone: engine-reported figures can differ from what fuel purchases show.
- Ignoring idle fuel: a truck that idles heavily may show poor MPG even if its driving is efficient.
- Comparing unlike routes: mountain routes, city routes and flat highway routes should not be ranked together.
- Short measurement windows: a single week can be skewed by one long wait or one heavy load.
- Missing fuel purchases: fuel bought outside the card program leaves gaps.
A sound approach reconciles fuel purchased against miles driven over a consistent period, separates idle fuel from driving fuel where the data allows, and groups trucks by duty cycle before comparing them.
Bottom Line
Truck fuel efficiency is the result of many small decisions: speed policy, idle habits, aerodynamic equipment, tire care, route and load planning, driver coaching and maintenance. No single change solves the problem. Fleets that measure honestly, compare fairly and fix the basics first usually make the most lasting progress.
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About the author: Luis Lopez is a Miami-based AI transportation consultant and logistics entrepreneur, the CEO of Go Hub.io Holdings Corp and subsidiaries, and host of the Freight Guru Podcast.