[BMWZ4RIDER]

I removed the lower outside grills set by removing the 2 screws on the wheel fender liner and then the under body cladding. After it was removed, I could push my hand inside the bumper housing. It was a tight fit BUT I was able to push on the release tabs 1 at a time for releasing the outside grill sets.

I too have experimented with the lower center air vent grill and by removing the under body cladding again, I was able to push my hand inside to the center to reach the tabs. It was very tight and uncomfortable BUT beats taking off the bumper cover.