What are daytime running lights?

  • Why are they compulsory?
  • Do they drain my battery?
  • Parkers explains the tech

Daytime running lights (or DRLs) automatically switch on with the vehicle’s engine and are designed to operate during daytime hours. They are compulsory on all newly-designed cars and most other types of road-legal vehicles.

How do they work?

Daytime running lights are illuminated whenever the vehicle’s engine is running, only switching off or dimming when the headlights are turned on. This is because DRLs which take the form of powerful light-emitting diodes (LEDs) are too bright to be used at night, and may dazzle other drivers.

They will also dim when DRLs and side lights are combined.

Since DRLs automatically switch on and off with the vehicle’s engine, there’s no danger of forgetting to turn them off and running down the battery.

>> The Parkers guide to headlight bulbs

Are DRLs the same as foglights?

No, they are not. Fog lights must still be switched on manually when visibility is less than 100 metres.  

Do I need them?

All new cars and small delivery vans designed (or significantly updated) after February 2011 have DRLs fitted as standard. Research has shown that road users and pedestrians can detect vehicles fitted with DRLs better than those with just their dipped-beams switched on.

Cars and small delivery vans designed or updated before February 2011 are not required to have DRLs retrofitted.

Can I use DRLs instead of headlights?

No, DRLs must not be used in-lieu of headlights when it’s dark. Doing so would be breaking the law as your vehicle would be far less visible than when using regular headlights.

Similar to

LED headlamps, high-beam assist.

Looking for more jargon-busting motoring meanings? Head over to our Parkers Car Glossary page and take a look at our other definitions