Just fitted my BMW performance grills on my Z4..found the task fairly easy to complete and thought I would share a little tip for anyone looking to do so in the near future.
I got around the issue of not having enough space for the bottom 2 tabs but pushing the foam cover of the front bar downwards...this gave me ample room to put my fingers into the bottom tabs and release the grill
Once the first grill is out the second was fairly easy...again i slide the foam guard slightly down and removed the second...then put the foam guard back in place and put the grill in place
Apologies for the dirty car...not the best pics as its pretty grey and overcast
I got around the issue of not having enough space for the bottom 2 tabs but pushing the foam cover of the front bar downwards...this gave me ample room to put my fingers into the bottom tabs and release the grill
Once the first grill is out the second was fairly easy...again i slide the foam guard slightly down and removed the second...then put the foam guard back in place and put the grill in place
Apologies for the dirty car...not the best pics as its pretty grey and overcast

). The performance grills have a black surround, the stock grills have chrome (unless you have highline edition which comes with the black grills).