[globemaster3]

recap:
outside to inside you have your parking lights, normal headlights and (closest to the grill) high beams.
and your day time running lights (aka DRL) are your high beams on a low intensity.

so, when you pay $700 for the "xenon" lights - what is that *exactly*?

the 2003 3-series sedan book describes bi-xenon headlights as "BXH illuminate the road ahead and to the side with brilliant clarity. These low- and high-beam headlights also feature auto-leveling to adjust for varying passenger and cargo loads."

[for reference, let's talk about 1 'side' of the front of the car:]
so the $700 xenon option replaces the "standard [aka halogen]" bulbs (1xnormal headlight, and 1xhigh-beam) with "xenon" bulbs?

again, thanks for your patience.

 

[Sicily1918]

The Xenons replace your low beam (the outermost headlight).

Bi-Xenons replace the same, but when you switch on your high beams (not your flashers) they light everything in front of the car. In that situation, the inner halogen lights up only if DRL is enabled or when you're flashing (pulling the light stalk) your brights.

Xenon lights are, like halogens, filled with gas -- in this case, xenon -- it allows for a far brighter amount of light to be thrown in front of the car. The color is also closer to that of sunlight, allowing a better view of the road.