What are DRL's?
DRL's are the lights that turn on automatically when you start your car. They are currently standard on: GM, Lexus, Mitsubishi, Saab, Volvo, Volkswagen, Suzuki, and Subaru cars and trucks.
Why have DRL's?
DRL's are designed to make you easier to see during the day. They were originally created in other parts of the world that do not have very much ambient light compared to the USA in the 70s.
Why not have DRL's?
This answer could be different for everyone. Some may want to turn them off because they do not like the looks of them or agree with a number of people that say they are unsafe because the cars with them on make the cars without them harder to see. In Canada auto makers can put the DRL's on the high beams and the limit on DRL can be up to 7000cd. With that being said what do you do when a car with bright head lights is driving at you? By human nature you focus somewhere else most likely off the road!
What about the laws?
Right now there is no law requiring or banning DRL's.
What can I do if I want to have DRL's on my car that didn't come with them from the factory?
GM sells a kit that will convert your car to have DRL's. To purchase contact your local GM dealership.
How to disable your DRL's. (On Grand Prix's, other makes follow the link)
The easiest way to do this is to remove the panel on the driver side dash and unplug the 2 wire harness with the heat sink around it. Once unplugged (can be hard for big handed people) tape up the ends of the wires and your are FINISHED!
For an alternative method and other makes follow the link below:
DADRL - How To Disable DRLs
Side note: I will get pictures up sometime soon.