How much fuel does a truck use per 100 km

"What does yours use?" is the first thing drivers ask each other at the pump, and the question a fleet owner asks every time the fuel bill arrives. The answer depends on the vehicle, the load, the route and the driver, but modern trucks sit within known ranges, and there are clear reasons why the same truck uses 27 litres one week and 36 the next.

How much each type of truck uses

The values below are indicative, for modern (Euro 6) vehicles in normal conditions. Use them to check whether your figure is "normal", not as a target: two identical trucks on different routes easily differ by 15 percent.

For an international tractor-trailer that averages out at around 30 litres per 100 km. Volvo Trucks Serbia wrote about a driver at the carrier Jastim who averaged 24 litres per 100 km, which shows how much an experienced driver can save in the same truck.

Empty or loaded: how much the load changes consumption

Weight is the biggest single factor. A fully loaded 40-tonne truck uses on average 25 to 40 percent more than an empty one, because on every climb and after every braking the engine is moving more than twice the mass. So a truck that runs loaded one way and empty the other can have a perfectly good average while the loaded leg is high.

In practice: do not compare consumption between vehicles on different routes. Compare the same vehicle on similar routes, or drivers on the same vehicle, and always together with the load.

What else affects consumption

• Speed. Air resistance grows with the square of speed. On the motorway the difference between 80 and 90 km/h is worth a few percent of fuel, while arrival time barely changes.
• Route and terrain. Hilly routes, city driving and frequent stops raise consumption more than any technical detail.
• The driver. Anticipation, early gear changes, coasting and cruise control. Training and monitoring eco-driving in fleets usually brings 5 to 10 percent.
• Tyres and pressure. Pressure below the specified level increases rolling resistance, and with it consumption, and wears tyres faster.
• Aerodynamics. Spoilers, side skirts and the gap between tractor and trailer; an open tarpaulin or an empty container chassis use noticeably more.
• Idling. An hour with the engine running while parked burns fuel while the odometer stands still (more below).
• Winter. A cold engine, winter diesel, heating and snow on the road usually add a few percent.
• Maintenance. A clogged air filter, poor wheel alignment and worn tyres slowly add litre after litre.

How much a truck uses when idling

A truck engine at idle uses roughly 2 to 4 litres an hour, more with the air conditioning on or when the engine is used to heat the cab. Ten hours parked with the engine running is 20 to 40 litres without a single kilometre driven, and in the average per 100 km it shows up as "the truck uses too much".

A separate cab heater (Webasto or similar) uses far less, roughly 0.1 to 0.3 litres an hour depending on model and output. For a winter night that is an order of magnitude less than an idling engine. A vehicle tracking system records engine idling per vehicle and per driver, so you can see exactly where that fuel goes.

AdBlue: how much a truck uses

Euro 6 trucks use AdBlue to clean the exhaust. Consumption usually runs at 3 to 6 percent of diesel consumption: a truck using 30 litres of diesel per 100 km uses around 1 to 2 litres of AdBlue. It is not a big cost, but it belongs in the cost per kilometre, and a sudden drop in AdBlue use can point to a fault in the system.

Does the truck brand make a difference

Volvo, Mercedes, MAN, Scania, DAF, Iveco and Renault are close to each other in recent generations: in the same conditions differences are usually a few percent and depend on the configuration (engine, gearbox, axle ratio, aerodynamic package). Load, route and driver change consumption far more than the badge, so it is smarter to compare your own trucks on your own routes than to trust the brochure.

How to calculate your real consumption

The most reliable manual method is the full-tank method: fill the tank to the top and note the odometer, drive, then fill to the top again and note how many litres went in and how many kilometres were driven. Consumption is:

litres ÷ kilometres driven × 100 = litres per 100 km

Example: 312 litres for 1,040 km gives 312 ÷ 1,040 × 100 = 30 l/100 km. The fuel consumption calculator does the maths for you, together with the cost per kilometre. Measure over several trips, not one: a single top-up before or after the pump's cut-off can move the result by a couple of litres.

What 100 km costs

Cost per kilometre is consumption per 100 km times the price per litre, divided by 100. For a tractor-trailer using 30 l/100 km, at an example price of 200 dinars per litre:

Over a year the difference becomes serious. A truck covering 120,000 km at 30 l/100 km uses about 36,000 litres. Every litre per 100 km less is about 1,200 litres a year per truck, and on a ten-truck fleet that is 12,000 litres. That is where knowing the exact figure, rather than an estimate, pays off.

A fuel card is not the same as consumption

Many companies calculate consumption from fuel bills or fuel card reports. That shows how much was paid, not how much the truck used. The difference is refuelling outside the card, top-ups that are not recorded and, unfortunately, fuel drained from the tank. In the records it all looks the same: "the truck uses 38 litres".

The accurate picture comes from the vehicle itself: consumption over the CAN bus, or a fuel probe in the tank that records every refuelling and every drop in level. How draining is detected is explained in how to prevent fuel theft in a fleet.

How a fleet tracks consumption

With fuel consumption tracking, consumption is not worked out at the end of the month; it is visible per vehicle, per trip and per driver:

• consumption per 100 km and per engine hour, with kilometres driven and idling time;
• refuelling and drops in tank level, with location and time;
• an alarm when the level drops sharply while the vehicle is parked;
• a comparison of drivers on the same vehicle, the basis for a conversation and eco-driving training;
• reports by e-mail, with no manual matching of receipts and mileage.

For trucks in international transport the same is visible abroad, with truck GPS tracking and the tachograph in one place.

Frequently asked questions