Originally Posted by subiePrezaWRX
YWhat I meant was, when the engine is on, how is the headlight "off" setting any different then the "on" setting (off/on/headlight), other than turning on the backlighting to the instrument panel?
The difference is that when you turn the headlights on, the headlights are on. When you turn the parking lights on, the parking lights are on. When you have the headlights and parking lights set to off, the daytime running lights are on.
If you have the headlight switch set to "off", then you have no reason to touch it unless you want your headlights on.
If you have the headlights switched on, there's still no need to touch the switch, because they'll turn themselves off as soon as you remove the key. That is, unless you switch them on after removing the key.