Re: 156 Xenon headlamps
There are actually 2 types of automatic headlamp levelling, Static and Dynamic.
Static is by far the most common system as it requires less sensors, ECUs, and will work with standard levelling motors. It is also significantly cheaper!! It works by assessing the pitch of the vehicle whilst static when the ignition is turned on, and aims the headlamps accordingly. It does this only once, at the beginning. This is what you see when the lamps raise up and then dip to a new level. It does not adjust the aim as the car is in motion, so your headlamp beams will pitch up and down with the vehicle as normal. It only means that you don't have to consider using the load level switch to account for vehicle loading.
Dynamic levelling, as the name suggests, dynamically aims the headlamps as the car is in motion. It is actually damped quite a bit as it is pretty nauseous to drive along with the headlamp beam remaining still whilst all your sensory organs are telling you that you are pitching up and down. It works really well and does stop oncoming drivers being dazzled. Unfortunately it is the only way to control this problem of HIDs, however, it is only really found on very high end vehicles.