Eco-Safe Driving: The Rules, Numbers and Test Questions
Fuel efficiency, emissions and eco-driving techniques — a growing category on the UK theory test and the environmental impact of vehicles.
The DVSA has been steadily increasing the number of environmental questions on the theory test. They cover fuel efficiency, emissions, and how you can reduce both.
Driving style: the biggest lever
- Anticipate the road ahead — smooth braking and acceleration save more fuel than any gadget.
- Change up gears early — high revs waste fuel.
- Cruise at a steady speed. Motorway fuel economy peaks around 55–60 mph and drops sharply above 70.
- Avoid short journeys from cold — a cold engine uses roughly twice as much fuel per mile.
- Coast in gear where safe — modern injection systems cut fuel to the engine when you lift off the accelerator with a gear engaged.
Vehicle maintenance
- Under-inflated tyres increase rolling resistance and fuel use. Check pressures monthly.
- A dirty air filter can raise fuel consumption noticeably.
- Roof racks and roof boxes add drag — remove them when not in use.
- Air conditioning uses fuel; open windows at low speed, use AC on the motorway (windows create more drag at speed than AC uses in fuel).
Emissions and low-emission zones
Many UK cities have Clean Air Zones or ULEZ schemes. Non-compliant vehicles pay a daily charge. Diesels registered before 2015 and petrols before 2005 are usually non-compliant. This has started appearing on the theory test.
Idling
It is illegal to leave a vehicle's engine running while stationary on a public road unnecessarily. Turn the engine off if you'll be waiting more than a minute or so — at level crossings, in queues, or when parked.
Electric and hybrid vehicles
Electric vehicles produce zero tailpipe emissions and are exempt from ULEZ charges. They are also very quiet — a specific test question notes that pedestrians and cyclists may not hear them approaching, especially at low speed.