CPC Eco-Driving — Questions and Answers
Question 1: What is the most fuel-efficient way to accelerate in an HGV?
- Accelerate as quickly as possible to reach cruising speed
- Accelerate smoothly and progressively, using the green band on the rev counter (Correct answer)
- Use the lowest gear and highest revs
- Alternate between accelerating and coasting
Correct answer: Accelerate smoothly and progressively, using the green band on the rev counter
Smooth, progressive acceleration within the green band (typically 1,000-1,500 rpm) is the most fuel-efficient approach. Aggressive acceleration wastes fuel and increases wear. Block gear changing (skipping gears) can also help when appropriate.
Question 2: How does anticipating traffic conditions ahead help reduce fuel consumption?
- It does not help with fuel consumption
- Reading the road ahead allows the driver to maintain momentum, reduce unnecessary braking and acceleration (Correct answer)
- It only helps reduce journey time
- Anticipation is only useful for safety, not fuel saving
Correct answer: Reading the road ahead allows the driver to maintain momentum, reduce unnecessary braking and acceleration
By looking well ahead and anticipating traffic flow, traffic lights, roundabouts, and hills, drivers can maintain momentum, coast where appropriate, and avoid harsh braking followed by heavy acceleration. This 'smooth driving' approach can save 10-15% on fuel.
Question 3: What is the most fuel-efficient cruising speed for most HGVs?
- As fast as legally possible
- Between 50-56 mph (the speed limiter range), as fuel consumption increases significantly above these speeds (Correct answer)
- Below 30 mph at all times
- It makes no difference what speed you travel at
Correct answer: Between 50-56 mph (the speed limiter range), as fuel consumption increases significantly above these speeds
Most HGVs are most fuel-efficient at steady speeds between 50-56 mph. Above this, aerodynamic drag increases significantly (doubling for every doubling of speed). The speed limiter (56 mph for most UK HGVs) effectively caps the maximum cruising speed.
Question 4: How does cruise control help with eco-driving?
- It does not help with fuel efficiency
- It maintains a constant speed, preventing the driver from unconsciously varying speed, which wastes fuel (Correct answer)
- It automatically changes gears for maximum power
- It reduces engine temperature
Correct answer: It maintains a constant speed, preventing the driver from unconsciously varying speed, which wastes fuel
Cruise control maintains a steady speed, eliminating the small speed variations that occur during manual throttle control. This consistency reduces fuel consumption. However, it should be disengaged on hilly terrain where the driver can manage speed more efficiently.
Question 5: Why should unnecessary electrical loads be switched off to save fuel?
- Electrical systems do not use fuel
- The alternator requires engine power to generate electricity — more electrical load means more fuel consumption (Correct answer)
- Electrical systems use a separate battery that does not affect fuel
- Only the headlights affect fuel consumption
Correct answer: The alternator requires engine power to generate electricity — more electrical load means more fuel consumption
Every electrical system in the vehicle is ultimately powered by the engine via the alternator. Running unnecessary electrical loads (air conditioning, heated screens, extra lights) increases the load on the alternator, which requires more engine power and therefore more fuel.
Question 6: What is 'block gear changing' and how does it benefit fuel economy?
- Changing gears only when the engine stalls
- Skipping intermediate gears when changing up or down, keeping the engine in its efficient range (Correct answer)
- Never changing gear during a journey
- Using the clutch without pressing the accelerator
Correct answer: Skipping intermediate gears when changing up or down, keeping the engine in its efficient range
Block gear changing means skipping gears (e.g., going from 3rd to 5th or 8th to 5th) rather than changing through every gear sequentially. This keeps the engine in its most efficient rev range and reduces the time spent at inefficient RPMs during gear changes.
CPC Eco-Driving
What is the most fuel-efficient way to accelerate in an HGV?