Having bought the new interior for my Z4, I was left with the challenge of switching the leather inserts from one set to the other. My cards were extended leather, and the supplied ones were the basic style and also slightly damaged. Very little information I could find on how to do it, so was left to my own devices with a diverse collection of tools. I've stripped down a Z3 interior, which is kids play compared to this. Below is a pic of the existing extended leather cards, and below that the donor cards. The aim is to replace the red leather panels with the yellow ones. There is an almost continuous seam of plastic weld around the area of the leather insert which needs to be broken. Next off is a picture of the door panel with the leather removed. This show well attached they are, and how much plastic weld needs to be broken to get them apart. The white line shown is the adhesive I used to fix the panels back on, it exactly follows the seams that were broken so you can see how much effort is involved. So, is there a technique to splitting them? Not really, but the plastic panels are incredibly strong and the plastic seams are a weak point. A combination of Dremel cutting disc, broad flat blade screw driver and brute force seemed to work best. Using the Dremel cut a slot in the weld enough to get the screw driver head in, then twist it and the next inch or so would break open. Rinse and repeat, with varying levels of effort involved at different points. The speaker section (round area to the right) was tricky as the plastic would move around as you tried to twist the screw driver. The rectangular section was bonded more securely as it's where the air bag pops out of the panel. This is a close up of the plastic "seam" where the two meet. This pic gives a reasonable close up of the technique I used. You can see the molten plastic from where the Dremel disc went in first, followed by the screwdriver. The first panel took me an hour, but the fourth about 20 minutes once I'd perfected the process as best I could. The plastic on both the panel and the door card is really strong so could get a bit more physical than I was expecting. The reverse of a leather insert, again showing the seam. Two sets of leather panels after much effort. I spent 20 minutes in B&Q looking at options for glue and settled on Evo-Stik Seriously Strong Stuff Ultimate Adhesive. Various reasons, it worked with plastic, is high bond and had 10 minutes of adjustment before it started to go off. Then it had a 24 hour curing period which was fine as I had plenty of time. Once the glue was applied, I created a basic jig to hold everything in place (assembled out of what was to hand in the patio) Worked like a dream. As I say a real pain in the backside, but totally worth it. Would I want to do it again... Hell No!! ...and finally in situ..