In my new ’95 945 the rear fog light (singular) work like this: (btw, there is no separate front fog light)

Head light switch off – just like driving at night, all the lights on except the brights won’t work and the rear fog light won’t come on if switched on.

Head light switch in the parking lights position - same as above except the parking lights stay on if the ignition switch is off.

Head lights switch in the on position, all the lights ON (I would hope), except when the ign sw is off. Brights work and the fog light (only one) works. There is a plastic base but no lamp socket on the passenger side.

Everything I have seen always recommends driving in the fog with only the regular headlights on. Hi-beams will shine up too high, illuminate the fog only, and block vision. I think John A said that that there is normally only one rear fog light, only on the drivers side, to be used only in fog or rain just to make the car more visible and to indicate that it is not the brake lights. This may be a European “thing”, not sure, but not DOT. Until I got the brick I would say that an idiot is riding the brakes and one bulb is burnt out.

(I wonder if the fog light will turn off if I turn on the brights.)

Looks like the different years and models are all wired just a little different…… like us.