[ozorion]

I didn't get the bi-xenon lights myself so I can't speak for that decision (though I noticed that the 116i I've been lent during this week has a DRL option in the settings even with Halogens), but I thought I'd through in here that some other makes of vehicle actually don't have the option - if you have bi-xenon lights and the car is switched on, your day-time lights are on. Not to unlike how motorcycles work.

It's apparently a safety feature to assist pedestrians and other vehicles spot your car in conditions that would otherwise make it hard to see (like fog or heavy rain).