According to available research, Daytime Running Light (DRL) is important for road safety. All road users, including pedestrians, cyclists and motorcyclists, can detect, recognize and identify vehicles equipped with DRL, better and earlier. The mandatory introduction of dedicated DRL was discussed in the Commission's High Level Group CARS 21 (“Competitive Automotive Regulatory System for the 21st Century”) with high level executives from Member States, industry and non-governmental organisations (NGOs) and got unanimous approval. The Directive, which has been adopted today, foresees that from 7 February 2011 onwards all new types of passenger cars and small delivery vans will have to be equipped with DRL. Trucks and buses will follow 18 months later, i.e. August 2012.
On vehicles equipped with Daytime Running Light, this light is automatically switched on when the engine is started. When it is dark the driver has to switch on the driving lights manually. In this case the DRL goes off automatically.
This is just a paste from a website but next time you're out driving in daylight just notice how much sooner you will see a car with its lights on, especially the new Audi DRL's or BMW and new Golf!