It was really cold (20-30 ?F)the other day in my mom's X5, and the left light was slightly flickering. After the car heated up the flickering stopped. This flickering really was not noticeable at all (noticed it because of the light on the garage door). You'd have to look really hard to notice it.

On another note, in the same cold weather, the 330Cic we have had a little trouble from disengaging the right hi-beam. It would lag after the left headlight (the left headlight would go from hi-beam to low beam, with the right headlamp following around 1 second later)...

Point I am trying to make is, cold weather does funny things to xenon headlights...