Fuel-efficient driving is a mandatory subject in Driver CPC training (code 95) and a separate continuing vocational education goal. Here is the physics behind consumption — air resistance, rolling resistance and mass — and the concrete driving techniques that reduce both fuel consumption, CO2 emissions and wear: anticipatory driving, correct gear selection, idling and cruise control.
Introduction
Fuel-efficient driving (eco-driving) is about moving the same goods with as little fuel as possible. For a truck, fuel is one of the heaviest operating costs, and every litre burnt produces CO2. Therefore, "rational fuel consumption" is also a statutory subject in Driver CPC training: the EU directive on Driver CPC training (code 95) sets requirements for training in safety-based, fuel-efficient driving. The good news is that what saves fuel is almost always also what is most safe: a steady, forward-looking drive.
Where the fuel goes
The engine's work is used to overcome three resistances plus losses in the engine and drivetrain. Understanding the three resistances is key to driving economically, because they grow very differently with speed:
- 01Air resistance — grows with the square of velocity (F ∝ v²). At motorway speed, air resistance is the dominant resistance for a lorry, and therefore speed has such a major impact on consumption.
- 02Rolling resistance — comes from tyres and road and increases roughly linearly with weight. Low tyre pressure increases rolling resistance noticeably.
- 03Acceleration/climbing resistance — the energy it costs to get the mass moving or lift it up a hill. With a fully loaded articulated vehicle of up to 56 tons, the mass is large, so every unnecessary braking and re-acceleration costs.
Anticipatory driving — the biggest single factor
The most important eco-driving technique is to read the traffic far ahead, so you avoid unnecessary braking. Every time you brake, you convert movement energy (which you have used fuel to build up) into heat in the brakes — and afterwards you must use fuel again to get back up to speed. A driver who sees a red light, queue or roundabout in good time and eases off the accelerator, coasts forward on the vehicle's own motion energy instead of driving right up and braking hard.
- 01Look far ahead — plan for what happens 10–15 seconds ahead, not just in front of the radiator grille.
- 02Release the accelerator early — let the vehicle coast towards a traffic light or queue rather than holding speed and braking late.
- 03Avoid 'accordion driving' — steady speed uses less than constant acceleration/braking.
- 04Exploit the terrain — gain a bit of speed going up a hill and let it roll down the other side instead of braking.
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