Daytime running lights (DRLs) are required by law in Canada, Denmark, Iceland, Sweden and Norway. Any other countries that require them I'm not aware of. They are fitted as standard to many other manufacturers' cars, such as Audi and GM.

As a result, and contrary to what bigmouth_strikes is saying, they *cannot* always be turned off, as to do so would be illegal. In Canada, my parents owned a Toyota Camry with DRLs and they could not be switched off. Here in Wales, I own a Volvo 440 and it cannot have its DRLs switched off either - at least, not without going under the hood with a screwdriver.

Much of this node seems more concerned with people being idiots (and not just when it comes to driving) than the actual function or benefits of DRLs. For one thing, they shouldn't be as intense as normal 'dipped' headlights. I'd say my 440's DRLs are roughly half as bright.

A definite benefit of the lights is that they make it clear whether the car is running or not... someone might be parked awkwardly and sitting in their car, but if their DRLs are on, that gives you advance warning that the engine is almost certainly running and that they could move at any moment.

You know when you're out driving in the evening, and someone in a dark-coloured car goes past and you barely saw them because they've not switched their headlights on yet? DRLs remove that danger, providing crucial visiblity to cars in motion during any reduced-visiblity situation such as rain, spray, sunrise/sunset.

Not all cars have them fitted - when I drive a car without the running lights, I switch the parking lights on to compensate. DRLs also result in a dirtier car, as insects can be drawn to their glow and get splatted. Finally, they are a small extra drain on the battery, although some cars are configured to not switch the lights on until 10 seconds after the engine is started.

DRLs make for safer motoring for everyone, like it or not, be you inconsiderate or careful on the road. The Australian RAC took part in a study in which 80 vehicles from a nursing association were fitted with DRLs, with a 10 percent decrease in accidents. The Association of Drivers Against Daytime Running Lights argues that drivers in the United States don't suffer from "deficient lighting conditions" like in other countries, and therefore, DRLs should not be used. They make a series of increasingly desperate arguments against the lights, never proving them harmful but seeing them as merely ineffective. Surely, if they save one life, you can live with them? HowStuffWorks claims that 406 million gallons extra would be burned in the United States alone if every car there had DRLs. The DADRL would say that therefore, we should forgo own own safety in favour of a few gallons each per year, and the resulting reduction in pollution.

Sources: www.lightsout.org - the DADRL website
www.actionimports.com.au - fitters of DRLs in Australia
www.howstuffworks.com/question424.htm - how much fuel do the lights burn?