I think it might be part of one of the sport aero packages perhaps.
On non-M cars, this always looks to me like someone stole the BMW's
grill during the night, but then tastes do differ.
=)
Still, it's easy enough to replace the grilles as they are literally
just snap in place and cost peanuts to replace ('peanuts' being $12 for
an 'official' replacement chrome insert on an E46 coupe).
>> Stay informed about: X5: black radiator grid