It's a battery save feature.
Originally Posted by nhhiep
they are on if the car is off, but you press the On/Off button.
another weird problem, my radio keep shutting itself down if the car is off. this happened to me last time I waxed my car with the music on, and it seems to shut off every hr or so. is this a feature to save battery or my car has problem (nothing new with BMW uhh? )