Is yours a single light between the visors? My 09 Zetec has the door light and each side of it a map light. But there was no rear light so I fitted one myself at the rear of the centre console fed off the footwell lights. I would imagine your roof space behind the lining would be the same and hope it's a simple swap to include the map light version.
It connects to sensors in the seat and if you clench your bum cheeks it will switch to sport mode with increased torque and a higher fuel to air ratio and crank up the stereo with some serious drum and bass..
But if it senses a fat ar5e after you have just been to McDonalds it switches to lazy mode, puts on some soul music and lowers the window so you can lean your elbow out and do a slow nod to the girls.