Daytime running lights (DRLs) are designed to make your vehicle more visible in bright, daytime conditions. They should come on automatically when you start your engine.
- Bright enough to be seen clearly in daylight, DRLs are too bright to be used at night when they would cause dazzle
- They go off automatically when you switch your headlights on
- They don't have to be separate lights and are sometimes combined with the front position lamps (side lights). If this is the case, the DRLs dim when the headlights are turned on
- If your daytime running lights are very close to your indicators, the DRL will turn off while the adjacent indicator flashes
- Performance requirements for DRL are defined in UN ECE Regulation 87
- Operating requirements are defined in UN ECE Regulation 48
Fitting DRL yourself
Thanks to European regulations, they’ve been fitted to most new cars and vans since 2011, and new trucks and buses since August 2012, but EU regulation applies to new cars only.
There’s no requirement to retrofit daytime running lights, but kits are available if you wish to do so. Look for an approval mark on the lamp which includes the letters 'RL'.
If you’re fitting daytime running lights they should be installed so that they come on with the engine and go off when headlights are turned on.
Want to know more?
- The Volvo 240 was the first car in Britain that could be said to have had DRLs – brighter bulbs alongside the standard sidelights were lit all the time unless the driver turned on the sidelights
- In the mid-80s the government launched plans for 'dim-dip' lighting – for use in urban areas at night – but these were scuppered when European standards couldn't be agreed; ‘dim-dip’ switched on headlights at reduced brightness when the ignition and side lights were on
- Much discussion followed about whether cars across Europe should have their headlights on all the time, and many countries introduced local rules
- By 2006, 12 countries had laws requiring headlights on all year round including:
- Sweden since 1977
- Iceland, Latvia, Macedonia and Norway since around 1980
- Denmark since 1990
- Romania, Slovenia and parts of Portugal since 1998
- Lithuania, Slovakia and the Czech Republic required daytime use of headlights in the winter only while Hungary and Italy required DRLs outside built up areas
- The UK has never introduced a rule requiring daytime use of headlights
Benefits of daytime running lights
In 2006 the European Commission published research into the effectiveness, costs and benefits of introducing dedicated DRLs.
- Those in favour of DRLs claimed significant potential to reduce road deaths and serious injuries
- Those against objected to the constant glare of headlights and worried that motorcycle riders might become less conspicuous
- There was concern about increased fuel costs too
The Commission’s study suggested a lot of casualties could be prevented across the EU with a positive benefit-to-cost ratio, once the costs of fitting lamps and the environmental cost of running them was taken into account.
- A later UK (Department for Transport) study confirmed the Commission's findings on accident reduction, but cast doubts about whether the benefit would outweigh the costs
- The UK study also found that dedicated DRLs could improve the visibility of cars in dim light without reducing the visibility of motorcyclists
Fuel consumption
The alternator – electrical generator – is driven by the engine and spins all the time but it doesn't always consume the same amount of power from the engine. When the electrical load on the alternator increases, more power is required to turn it and your fuel consumption increases.
- Light Emitting Diodes (LED lights) only consume a fraction of the electricity taken by a normal headlight
- Use of dedicated DRL instead of driving with headlights or sidelights also means that your tail lights and instrument lights aren’t on during the day
27 February 2017