See those bright LEDs? They are not your headlights, no matter how bright you think they are. DRLs and headlights are two completely different things.
This R8 has its headlights on. How do we know? It’s because the headlights are bright enough to somewhat “blind” the camera. Just think of it as if you saw this car in your mirrors. Is there so much light coming from the headlights that light rays going off in different directions are visible.
This R8 doesn’t have its headlights on. How do we know? Well, the headlight beams aren’t on, obviously. But more importantly, you can see that the DRLs aren’t “blinding” the camera.
DRLs are made for just making sure you’re visible to other drivers in the daytime. So, if a driver is basically blind, at least he or she will see some light and know there’s a car there.
Headlights are made for darker days and nighttime driving. So if it’s cloudy/foggy, feel free to put on your headlights. But during the night, DRLs aren’t going to cut it. Like I mentioned before, DRLs are just to let others know your car is there. Headlights will let you see a couple hundred feet in front of you, and this is obviously going to be safer than having, maybe 5 feet, of visible road in front of you at night using DRLs.
Most importantly, you could get away with using LED DRLs at sunset (but you shouldn’t), but with standard halogen DRLs like most cars still use, you won’t see crap at night. It actually scares me to see someone using something like these at night:
Because obviously these don’t cast any light. And remember, when you use your DRL setting, your taillights probably aren’t going to be on. So you’re posing a danger to yourself by not having full vision ahead of yourself, and a danger to others around you, because they won’t see your car if it doesn’t have tailights on.
Just look at how much more light you get if you turn on your headlights.
TL;DR: Use good judgment and know the DRLs are for daytime and that headlights are for driving in the dark.