I installed this on my '05 x3, and it involved a bit of drilling through the side cover in the cargo area. NOt hard, but it was a bit frightening taking a drill to the car. They worked OK, but flexed enough when I had very heavy bags that I never used them much. I had some bags pull off the grovery gripper.
From the phto for the F25 series x3, it appears that attach to the rear of the back seat. The older method work not work wit htis because I had to have access to the back of the creaws to attach nuts. I would not want to have to take my seats apart to install them.
Some sites have the PDF installation instructions, so you can see ahead of time how they are installed. I would check that out before buying them.