There must be a way for it to "contact" without an actual physical/eletrical contact, sort of like how an electronic door lock on a building can be activate by waving a plastic card key next to it without any sort of physical/electrical contact. It does require that the key and the receiver be close enough though. The very close proximity of the plastic key and the ignition must be close enough. I'm not an engineer; just an educated guesser.

In any event, it has to be something like this because the X5 should not start without a chip in the black plastic key otherwise what's the point of having a chip in any of the keys?

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