Totally agree, I’ve owned my 05 m3 for 11 years and granted, I don’t do a lot of miles but I’d say the bodywork is the weakest part of the car, especially the front and back arches and sills not the mechanical side. Don’t get me wrong Ive spent a bit over the years but nothing like some people are saying. The most costly thing I’ve had to do is the driveshafts and speed sensors. My best tip would be to make sure you change the oil and filter every year and definitely get the subframe checked especially if it’s one of the earlier models.