PCV Environmental Awareness and Fuel Efficiency 2 — Questions and Answers
Question 1: A PCV driver is approaching a red traffic light at a bus stop. What is the most fuel-efficient approach?
- Maintain speed and brake sharply at the stop line
- Lift off the accelerator early, coast towards the light, and allow the vehicle to decelerate naturally (Correct answer)
- Use the highest gear possible to maintain momentum
- Rev the engine in neutral to keep it warm
Correct answer: Lift off the accelerator early, coast towards the light, and allow the vehicle to decelerate naturally
Coasting early to a red light uses less fuel than maintaining speed and braking late.
Anticipating a red light or bus stop and lifting off the accelerator well in advance allows the vehicle's inertia to carry it forward with minimal fuel use. In modern vehicles with fuel cut-off, the engine uses virtually zero fuel when decelerating in gear. Late, sharp braking wastes the kinetic energy already built up and uses more fuel to re-accelerate. This eco-driving technique reduces both fuel use and brake wear.
Question 2: What does the Euro VI emission standard primarily target in bus engine exhaust?
- Carbon dioxide (CO2) only
- Nitrogen oxides (NOx) and particulate matter (PM) (Correct answer)
- Noise pollution from the engine
- Sulphur content of diesel fuel
Correct answer: Nitrogen oxides (NOx) and particulate matter (PM)
Euro VI standards set strict limits on NOx and particulate matter (PM) emissions from diesel engines.
Euro VI is the most stringent European emission standard for heavy-duty vehicles. It sets tight limits on nitrogen oxides (NOx — linked to respiratory disease) and particulate matter (PM — linked to cancer and cardiovascular disease). Euro VI buses emit roughly 80% less NOx than Euro V vehicles. Compliance with Euro VI is required for free access to most UK Clean Air Zones.
Question 3: How can a PCV driver reduce fuel consumption when driving on the motorway?
- Drive at 80 mph to complete the journey quickly
- Maintain a steady speed within the speed limit, use cruise control if fitted, and maintain a safe following distance to avoid unnecessary braking (Correct answer)
- Frequently overtake slower vehicles to maintain momentum
- Keep the bus in a lower gear to use engine braking on flat roads
Correct answer: Maintain a steady speed within the speed limit, use cruise control if fitted, and maintain a safe following distance to avoid unnecessary braking
Steady motorway speeds with minimal braking events and cruise control use significantly less fuel than variable high-speed driving.
Aerodynamic drag increases with the square of speed — driving at 60 mph rather than 70 mph can reduce fuel consumption by 15–20% on a large vehicle. Using cruise control on suitable motorway sections maintains a steady speed without the micro-variations of manual throttle use. Maintaining safe following distance avoids the accordion effect of frequent braking and acceleration that wastes fuel.
Question 4: What impact does carrying unnecessary weight on a bus have on fuel consumption?
- No impact — bus engines are designed for maximum load at all times
- Additional weight increases rolling resistance and the energy required to accelerate, increasing fuel consumption (Correct answer)
- Extra weight improves traction and reduces fuel consumption on wet roads
- Weight only affects fuel consumption on hill sections
Correct answer: Additional weight increases rolling resistance and the energy required to accelerate, increasing fuel consumption
Additional weight requires more energy to accelerate and increases rolling resistance, increasing fuel use.
Fuel consumption increases proportionally with vehicle mass. Unnecessary weight (e.g., carrying excess luggage, unsecured ballast, or full water tanks that are not required) increases the energy needed for each acceleration event and elevates rolling resistance continuously. Operators should regularly audit what is carried in luggage bays and storage areas to minimise unnecessary mass.
Question 5: Which of the following best describes a 'Clean Air Zone' (CAZ) in the UK?
- A motorway section with reduced speed limits to lower noise pollution
- An area where the most polluting vehicles are charged to drive through, with the aim of improving air quality (Correct answer)
- A road specifically for electric and hybrid vehicles only
- A designation for rural roads with low vehicle traffic
Correct answer: An area where the most polluting vehicles are charged to drive through, with the aim of improving air quality
Clean Air Zones charge the most polluting vehicles to enter, incentivising operators to upgrade to cleaner fleets.
UK Clean Air Zones (introduced under the Environment Act and JAQU framework) designate urban areas where vehicles that do not meet minimum emission standards are charged a daily fee to drive. Category D CAZs include buses, coaches, and HGVs. The aim is to reduce NO2 and PM2.5 concentrations in areas that breach legal air quality limits. Operators must plan routes through CAZs and budget accordingly.
Question 6: What is the environmental benefit of an electric bus compared to a diesel bus?
- Electric buses produce zero tailpipe emissions, reducing local air pollution (Correct answer)
- Electric buses produce less noise but the same level of exhaust emissions
- Electric buses are lighter, which slightly reduces road wear
- Electric buses do not require any maintenance, reducing garage visits
Correct answer: Electric buses produce zero tailpipe emissions, reducing local air pollution
Electric buses produce no tailpipe emissions, directly improving air quality in the areas where they operate.
Battery-electric buses produce zero tailpipe emissions of NOx, PM, or CO2, making them transformative for urban air quality compared to diesel or even Euro VI diesel buses. While some CO2 is associated with electricity generation (depending on the grid mix), the direct local pollution reduction is significant. The UK government has committed to transitioning all new buses to zero-emission vehicles.
PCV Environmental Awareness and Fuel Efficiency 2
A PCV driver is approaching a red traffic light at a bus stop.
What is the most fuel-efficient approach?