Originally Posted by kindofblue
Looks to me like the spark plug cover.
Doubtful. The main spark plug is still in the center of the head with the large plastic cover over it like the current hexhead. It could be an secondary spark plug, I suppose, but some of BMW's tech literature says they've gone back to a single plug design without the secondary plug. My money is still on it being a fuel injector sitting right over the intake valve.