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Difficulty: Very hardEnvironmental Impact and Fuel Efficiency

A driver is preparing for a long motorway journey in a fully loaded vehicle with passengers and luggage. To minimise their environmental impact and achieve the highest possible fuel efficiency, they are evaluating different driving techniques and vehicle preparation strategies. Which of the following approaches demonstrates the most accurate and comprehensive application of eco-safe driving principles?

  1. Increasing the tyre pressures to the manufacturer's recommended laden settings, removing an empty roof box to reduce aerodynamic drag, and utilising engine braking on descents to activate the fuel cut-off mechanism.Answer
  2. B
    Depressing the clutch fully when descending long motorway gradients to allow the engine to idle and save fuel, while keeping tyre pressures at the standard unladen settings to maintain a comfortable ride.
  3. C
    Maintaining a constant speed of 70 mph to reduce the total engine running time for the journey, and ignoring an amber engine management warning light as only red lights indicate critical issues.
  4. D
    Leaving an empty roof box fitted for convenience on the return trip, and keeping tyre pressures at normal unladen levels to ensure the vehicle's suspension can absorb the extra passenger weight smoothly.

Answer

Increasing the tyre pressures to the manufacturer's recommended laden settings, removing an empty roof box to reduce aerodynamic drag, and utilising engine braking on descents to activate the fuel cut-off mechanism.
The correct answer synthesizes three vital eco-safe principles. First, adjusting tyre pressures for a heavy load minimises rolling resistance. Second, removing the roof box reduces aerodynamic drag, which is highly detrimental to fuel economy at motorway speeds. Finally, utilising engine braking allows the vehicle's electronic control unit to shut off fuel injectors completely, saving more fuel than coasting.

Step-by-Step Solution

1
Evaluate the impact of vehicle load on tyre preparation.
Tyre pressures must be increased to the laden settings.
A heavily loaded vehicle requires higher tyre pressures to prevent excessive sidewall flexing, which increases rolling resistance and fuel consumption.
2
Assess the effect of exterior attachments at motorway speeds.
The empty roof box should be removed.
Aerodynamic drag increases exponentially with speed; removing a roof box significantly improves fuel efficiency on motorways.
3
Determine the most fuel-efficient driving technique for descents.
Engine braking should be used instead of coasting.
Modern vehicles cut off the fuel supply entirely during engine braking, whereas coasting in neutral requires continuous fuel injection to keep the engine idling.

Key Concept

Eco-safe driving combines vehicle preparation (optimising aerodynamics and rolling resistance) with advanced driving techniques (maximising fuel cut-off via engine braking).
Estimated Time:1m 30s
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Topics

Environmental Impact and Fuel Efficiency

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