What is the fuel consumption of a heavy goods vehicle?

For any business operating HGVs, fuel spending is a major operational challenge and one of the biggest contributors to fleet costs. Fuel typically accounts for 15% to 30% of a fleet's overall expenses⁽¹⁾. Since many operational costs are fixed, fuel consumption remains one of the most controllable areas—making it a priority for fleet managers aiming to optimise budgets.

This guide explains how to calculate real fuel consumption and highlights practical actions to reduce costs and emissions across your fleet.

How to calculate the fuel consumption of an HGV

Manufacturers provide theoretical fuel consumption figures, but real-world conditions often cause significant variations. Several internal and external factors impact how much fuel a heavy goods vehicle uses.

Vehicle-related factors

Fuel consumption varies depending on:

• Vehicle size and configuration: larger and less aerodynamic vehicles naturally require more power, resulting in higher fuel use.
• Load weight and distribution: heavier loads increase engine effort, especially on gradients, raising fuel consumption noticeably.
• Tyre condition and tyre pressure: under-inflated or worn tyres create greater rolling resistance, making the engine work harder and burn more fuel.
• Vehicle maintenance: poor upkeep, clogged filters or old engine oil decrease efficiency, leading to higher fuel usage to maintain performance.

External factors

Fuel consumption is also influenced by environmental and operational conditions:

• Road types and driving environments: motorways allow steady speeds, while urban congestion, rural roads and hills require frequent acceleration, increasing fuel demand.
• Engine idling time: idling consumes fuel without adding mileage, often representing a hidden but significant source of waste.
• Driving behaviour: harsh braking, rapid acceleration and speeding all force the engine to consume more fuel while accelerating wear on components.
• Heating and air conditioning use: HVAC systems draw extra energy from the engine, which increases fuel usage over long operating periods.

Why accurate fuel monitoring matters

Manual calculations are often time-consuming and imprecise, especially when multiple drivers and vehicles are involved. That’s why many fleets rely on connected telematics systems like Geotab, which automatically capture real-time data on fuel use, idling and CO₂ emissions. Accurate monitoring allows fleet managers to make informed decisions that directly reduce operating costs.

Telematics gives you visibility into:

• Total fuel consumption over selected periods: this helps you understand long-term trends and seasonal variations, making it easier to forecast budgets and spot unusual spikes early.
• Fleet-wide average fuel usage: a clear benchmark allows you to compare vehicles and identify where efficiency improvements are needed most, leading to smarter asset decisions.
• Fuel use per vehicle: pinpointing high-consumption vehicles helps you detect potential mechanical issues, underperformance or mismatched vehicle types for certain routes.
• Fuel consumption per driver, even across multiple vehicles: this highlights safe, efficient drivers and reveals where targeted training can reduce fuel waste, improve safety and lower overall operating costs. In addition, telematics gives insight into harsh braking, rapid acceleration, excessive idling and route inefficiencies. These data points expose hidden cost drains, allowing you to act quickly and implement corrective measures that improve savings and sustainability.

Environmental impact of HGV emissions

Fuel consumption and emissions are directly connected. Heavy goods vehicles emit pollutants such as nitrogen oxides (NOx), carbon monoxide (CO) and particulate matter—substances known to affect air quality, public health and the environment.

Across Europe and many EMEA regions, emission standards have become increasingly strict. Today, all new HGVs must comply with EURO VI regulations, which push manufacturers to develop cleaner, more efficient engines. For fleets, this means:

• Lower fuel consumption
• Fewer emissions penalties
• A more sustainable and future-proof operation

Ultimately, reducing fuel usage doesn’t just cut costs—it also helps organisations meet corporate sustainability goals and regulatory expectations.

How to reduce fuel consumption in HGV fleets

1. Maintain vehicles consistently

Regular maintenance plays a decisive role in how much fuel an HGV uses. When vehicles run efficiently, they burn less fuel and experience less wear over time.

• Correct tyre pressure improves rolling efficiency: under-inflated tyres increase drag and force the engine to work harder, raising fuel consumption. Proper inflation reduces resistance and keeps fuel costs down.
• Clean filters and quality oil improve engine performance: a well-maintained engine breathes better and runs more smoothly, resulting in lower fuel usage and improved longevity.
• Preventative maintenance avoids mechanical resistance that increases fuel use: issues like worn brakes, failing injectors or clogged components create friction and inefficiency, regular servicing prevents these problems and preserves fuel economy.

2. Encourage eco-driving

Driving behaviour is one of the most influential factors affecting an HGV’s fuel use. Even minor changes can dramatically reduce consumption.

• Reducing speed decreases aerodynamic drag: higher speeds generate significantly more drag, forcing the engine to burn more fuel. Slightly slower speeds save fuel without major time loss.
• Smooth driving avoids sudden fuel spikes: harsh acceleration and braking are major contributors to wasted fuel. A smoother approach maintains momentum and improves safety.
• Eliminating unnecessary idling prevents wasted fuel: idling burns fuel without any productive output, reducing it immediately lowers operational costs and cuts emissions.
• Cruise control supports more consistent, efficient speeds: maintaining stable speed reduces variability, allowing the engine to operate in its most efficient range. Even simple adjustments matter. For example, reducing speed by just 10 km/h can save up to 1 L/100 km, delivering substantial savings across an entire fleet.

3. Use a fleet management system

Telematics platforms provide powerful tools to actively control and optimise fuel usage across all vehicles.

• Maintenance reminders ensure vehicles stay efficient: automated alerts help keep servicing on schedule, preventing mechanical issues that negatively impact fuel consumption.
• Driver feedback tools alert drivers instantly about inefficient driving: real-time feedback helps drivers correct behaviours such as harsh braking, speeding or prolonged idling, improving safety and fuel economy simultaneously.
• Route optimisation helps avoid congestion, closures and inefficient detours: smarter routing reduces travel time, prevents unnecessary mileage and ensures vehicles follow the most fuel-efficient paths.

By combining maintenance, coaching and smart routing, telematics delivers a continuous improvement cycle that lowers costs while supporting sustainability goals.

Sources: (1) IDAE