I thought they were illegal to use for driving, and are useless elsewhere.
I think they date back before every taillight had to be a reflector, so people would keep lights on while idling off the road, but dim the main lights to save the battery.
Yet, anything that costs money must be mandated or it would be dropped.
The car companies save every nickle.
So who decides this, and is there still a rationale for it?
I use mine whenever I’m on the highway during the day. Its just extra visibility for the other cars. And when it starts getting dark out, its just extra measure in case I forget to turn on the regular lamps.
I think they used to be required for parking in some suburbs on sidestreets.
This sort of makes sense to me, but it’s illegal here in California. This from the California Vehicle Code Chapter 2, Article 4:
You can’t drive with just your parking lights on. I agree with The Saint: I scratch my head on exactly when the law requires/allows their use, too.
What’s a parking light? Have I been missing something?
I understand that “daytime running lights” are now a feature offered on new cars. it would seem to be another money grab by the manufacturers.
Arent they needed as Hazard Warning lights?
“Parking lights” are probably better referred to as “running lights.” They’re the various little lights on your car that allow it to be seen at night. Generally speaking, they’re amber except at the rear, where they’re red. Based on my observation, it seems to be OK for parking lights to be white to the front (look at many Toyotas).
In American cars, at least, the headlight switch has three positions: off; parking lights only; and parking lights PLUS headlights. The OP was asking when, if ever, you are supposed to use that middle position.
Depending on the details of the vehicle, individual parking lights can do double/triple duty as turn signals, hazard flashers, and/or brake lights.
The headlights allow you to see things in front of you. Your parking lights allow others to see you from all directions.
Orginally posted by brad_d:
Parking lights and running lights are two different, AFAIK. I thought parking lights were the amber (yellow) lights sort of on the side. Running lights are like little headlights (white) that come on when the engine is on and the parking brake is released. I have a Saturn with running lights, and the parking lights (amber ones) only come on if I turn them on, or if the regular headlights are turned on.
Actually, there’s a thread about daytime running lights going on right now, and from what I’ve managed to gather, terminology is not particularly uniform. The lights on your car sound (to me) like what I’ve heard called “daytime headlights” “daytime running lights.”
Broadly speaking, lights on a car, boat, airplane, or whatever can be categorized as either (1) casting a beam so that the driver can see with it, (2) acting as beacons so that others may see the vehicle, or (3) signals (turn signals, brake lights, etc.). I’m under the impression that any of the category (2) lights on a vehicle can be generically referred to as “running lights”, even though the preferred term for them on cars seems to be “parking lights.” The little headlights that automatically come on (on cars so equipped) are referred to as “daytime running lights” because that’s precisely what they are: their primary intent is to allow others to see you, rather than to cast a beam.
You’re right, though, in that I should just stick with accepted terminology. 
Parking lights are what the industry calls 'em, so I oughta roll with it.
Had a French professor in college who said that in Paris you’re not allowed to drive at night with headlight beams on; you drive with only parking lights. This was the first time I heard the term “parking lights.”
But isn’t Paris “The City of Lights”?