CPC Eco-Driving & Fuel Efficiency

Question 1

Which driving technique most significantly reduces fuel consumption on a long motorway journey?

Accepted Answer

Using cruise control to maintain a steady speed and anticipating traffic flow to avoid unnecessary braking

Answer

Smooth, consistent speed — maintained using cruise control and anticipation to avoid harsh braking and acceleration — is the single biggest factor in reducing fuel consumption on motorways.

Question 2

How does tyre pressure affect fuel economy?

Accepted Answer

Under-inflated tyres increase rolling resistance, increasing fuel consumption by up to 3% per 10% under-inflation

Answer

Under-inflation increases rolling resistance as more tyre sidewall is in contact with the road; this directly increases the energy (fuel) required to maintain speed.

Question 3

What does 'anticipatory driving' mean in an eco-driving context?

Accepted Answer

Reading traffic situations well ahead and adjusting speed smoothly to avoid unnecessary stop-start driving

Answer

Anticipatory driving uses early perception of traffic conditions to decelerate gently and avoid braking fully, allowing momentum to be used efficiently and reducing fuel waste.

Question 4

Idling the engine of an HGV for extended periods is discouraged because:

Accepted Answer

It wastes significant fuel (approximately 2 litres/hour), increases emissions and can cause engine carbon build-up

Answer

An idling HGV engine typically consumes 2–3 litres of fuel per hour, producing unnecessary CO₂ and NOx emissions; switching off when stationary for more than 2 minutes is best practice.

Question 5

What is the effect on fuel consumption of increasing motorway speed from 56 mph to 60 mph?

Accepted Answer

A significant increase of approximately 10-15% due to the cubic relationship between air resistance and speed

Answer

Aerodynamic drag increases with the cube of speed; a relatively small speed increase above 56 mph causes a disproportionately large increase in fuel consumption.

Driver CPC Practice Test

Driver CPC Practice Test

CPC Eco-Driving & Fuel Efficiency