Replaced the front bumper cover (almost complete). 2008 Z4M Roadster. Interesting (at least to me) process notes:
1. After agonizing over the purpose, cost and installation procedure for the two FILLING INSERTS LEFT & RIGHT (51718044699 & 51718044700), it turns out that the bumper cover was supplied with these parts already attached.
2. The old bumper cover was removed without damaging the Supports, side panel front left and right, by carefully prying the bumper cover horizontal edge down with a plastic thingy, while pulling it away from the supports. Total fun.
3. Installing the new bumper to the supports went well by simply pushing the horizontal edge of the cover toward the supports until it snapped into place. Total fun.
4. I also replaced the Cover, bottom right and bottom left (51718046084 & 51718046083) and found that, although tedious, the installation was much less of a nightmare than I had anticipated.
5. I'm now deciding which fasteners to use to attach the wheel well liners to the bumper cover. The original bits are the 51717007296, but I've seen some mention that the 07147172274 bits provide a tighter and more secure connection. I'd usually opt for the originals, but I'm tempted by the siren song of "better".
6. I've also added some aluminum "skid plates" under the fangs to protect the paint and (hopefully) the fangs themselves. I've read both good and bad reviews of this addition, but I'm hoping that some overly cautious driving, on my part, will confirm the good reviews.
7. Cheers.