I copied the info below from a Roadfly post but it is exactly the route I chose (i have 3rd row seats that are down 99% of the time). The all weather cargo mat works great and fits perfect (it might seem just a tad tight if the second row seats are pushed all the way back). Note that the last few digits of the part number will change depending upon color! It is $58 from Circle BMW (they give nice internet discounts....ask for Chris in parts). Also...the beige color is not an exact match but you will will not even notice two days later....


I use the larger all weather cargo mat for x5s without the 3rd row. part number 82 11 0 417 985. the smaller one designed for use with the 3rd row seats up is useless since it only covers the under deck storage panel. and most likely if i were to carry anything messy in the back it would be with the seats down. The material is flexible enough that if i need to open the 3rd row, i either roll it up an stow it in whatever is left of the back. most of the time i dont roll it. i just bend it gently into a "U" shape and let it line up against the back seat and lower tailgate.