I see people driving around with the parking lights on during the twilight hours. What's the point? Do they really believe they are saving their battery or light bulbs when they do this?
Dylan: The purpose of parking lights is for parking in dark locations.
At one point in Britain it was mandatory to use parking lights when parked if there were no streetlights. I'm not sure if that's still the case. Some cars had a switch that could select only the offside lights to save energy.
Personally I think it would be safer for pedestrians if cars used only parking lights at night in areas with good streetlights. Pedestrians show up as dark against a lit road surface, cars are visible at great distance by their lights same as boats at sea (which are relatively dim, much like parking lights and tail lights). When cars use headlights, they illuminate a small area in front of the car but overwhelm the light from more distant vehicles and e.g. bicycles, and make it impossible to see pedestrians unless they are about to be hit (or have reflective clothing). Oncoming headlights tend to draw the eye away from other objects, making it hard to see hazards. Extremely bright street lights, such as are sometimes used at motorway intersections, can restore the status quo, but at considerable energy cost.
Of course, if you're the only car with just parking lights, you're at the same risk of being hit as a bicycle or pedestrian, so there's little incentive for any one driver to change their behaviour, even if the law did not mandate headlights.
Most of the time it is because people are idiots and either have running lights and are too lazy to switch to full headlights, or they are just too lazy to flip the switch all the way. Now the real purpose of parking lights is for parking. Say you are sitting outside waiting for someone. You want the lights on so they know where you are, or maybe they just are running in and out, but you turn off the headlights so you don't effect the drivers going by.
Nope. It's so I can see my dash gauges.
While outside lighting is still good enough to see clearly, my dash is shaded to the point they can't be seen well.
The other purpose for their existence is to comply with laws regarding parking at night: http://www.gencourt.state.nh.us/rsa/html…
The purpose is so that your car will be seen when parked on an unlighted road at night. Most states still have such a law on the books. I sometimes use them while driving around sunrise or sunset as other answers talked about. I have also lived in some towns that require their use during events when, at night, people drive through a neighborhood to admire Christmas decorations. Everybody is going slow enough so headlights are not needed and the parking lights tend not to drown out the Christmas decorations as much as headlights would. I never heard of their use being prohibitted, but I haven't driven much in California.
Studies indicate that there is a safety factor in having "running lights" on at all times. However, it can be dangerous to have full headlights on during hours of daylight, since that can hinder oncoming drivers. (BTW, it most states headlights must be used during "twilight," i.e., the 30 minutes or so before darkness.)
that is not the point. They want to be seen more clearly. Headlights can offset that during twilight.