As long as the donor car was also a 525i, there should not be too many probs except for the milage as David noticed... I replaced my 540iA instruments with the one from an M5 and it was quite a job to get all the readings right (had to swap the some of the dials as well). You can however re-programm the donor mother board for your BMW. Pls don't ask me how this is done. I found someone over a message board here in Germany who helped me out. Regards, Alexander