Like GoVols said "The seat slides forward to give the 3rd row more legroom(which it needs desperately) or to create more cargo space. The rearmost position is where it would be in a "fixed" location in an X without 3rd row."

I have 08 with 3rd row and the only thing i dont like is no AC air back there. There is an air vent but just blow air.lol Bmw needs to hook the back airvent into the car AC/Heater unit. You will not like seating back there in summer time. HOT