Finally got to the bottom of this. When you buy the 987-2 BiXenon HID lights from Porsche, you do NOT get any fog lights even though they are built into the lights. The lights have an HID projector section with a bi-Xenon HID bulb and a moving mask that gives low or high beam according to the position of the mask which is controlled by a magnet and solenoid. For some reason, known only to the gnomes of Stuttgart, Porsched decided to elimionate the fog light function (a separate projector lens with a yellowish beam that is focused low) and turn on the fog lights when the high beam is on to give a "fill" light in front of the car. This sounds like BS to me since if you are driving with high beams, you are probably moving fairly fast and what happens 10 feet in front of you has already happened!
No engineer worthy of the name or motor enthusiast would ever do this, so either the financial boys, the lawyers or DOT must have called this shot - but why? My 2009 E-class and 2006 SLK both have the same style Bosch projectors (dual)and true fog light functions on the switch.
Does anyone have a wiring diagram for the regular and bi-xenon headlights and headlight switch for the 987-2? Anyone else have a German driving machine that has this weird "feature"? Thinking about replacing the headlight switch with one from a non-HID car, but would like to see the wiring diagrams first.