Engine idling occurs when your vehicle’s engine is running but the car is stationary. Whether you’re waiting to collect someone, sitting in traffic, or parked outside a school, leaving your engine running while stationary is both environmentally damaging and often avoidable.
This seemingly harmless habit contributes to wasted fuel costs and unnecessary wear on your vehicle. If you're managing a fleet, tracking idling is key to optimising business fuel usage.
Why is idling bad?
Idling contributes significantly to air pollution and fuel waste. According to the Royal College of Physicians, air pollution causes around 40,000 deaths each year in the UK.
From a business perspective, a single diesel vehicle can waste up to one gallon of fuel per hour while idling. The RAC notes that idling for just 10 seconds can use more fuel than restarting the engine.
Looking to cut costs and emissions? Business fuel cards help you manage fuel spend more effectively.
Is it illegal to sit in your car with the engine running?
Yes, in many situations. Rule 123 of the Highway Code states that drivers must not leave their engine running unnecessarily on a public road. This can result in fines of up to £80.
Some councils are cracking down. The City of York’s “Kick the Habit” anti-idling campaign encourages residents to report offenders. While some question this approach, it mirrors the success seen in places like New York City.
Want to stay compliant and informed? Check out the RAC’s guide on engine idling.
When may you leave the engine running?
There are exceptions when leaving your engine running may be allowed:
- In slow-moving traffic
- During diagnostics or vehicle safety checks
- When de-icing your car, but only on private property
Still, if you’re parked and it’s safe to do so, the engine should be off.
If your fleet includes HGVs or LCVs, keeping engines running unnecessarily could cost your business thousands. Our HGV fuel card options are designed to help high-mileage businesses reduce waste and stay efficient.
How long can you keep your car running while parked?
There’s no official time limit, but more than 10 seconds is often too long. If you’re parked, the best practice is to switch off.
- Idling near schools or hospitals is especially discouraged
- Enforcement is increasing in many areas
- Idling unnecessarily while parked may count as an offence, even if you're inside the vehicle
Top tips to limit time spent idling
- Turn off your engine after 10 seconds of stopping
- Call ahead when collecting someone to minimise waiting
- Don’t warm your car up on the drive — it’s quicker to warm the engine by driving
- Avoid fines by switching off near schools or clean-air zones
- Install telematics for real-time idling data and alerts
- Consider switching to electric vehicles (EVs) to reduce emissions altogether
Unlike combustion vehicles, EVs don’t emit pollutants when stationary, but leaving them ‘on’ can still drain your battery. If you're transitioning to electric, our EV fuel cards simplify charging access and admin.
Future-proofing your fleet
With the UK set to ban the sale of new diesel and petrol HGVs over 26 tonnes by 2040, businesses should act now to reduce emissions and optimise fleet performance. Lowering idle times is a simple step toward that goal.
Start your journey today by exploring our fleet fuel card options or speak to our team for tailored advice.
