One of a unique feature about the BMW M3 and BMW M4 is the carbon fibre driveshafts that the vehicles come with. The driveshaft did help reduce the weight of the vehicle giving it a better performance but according to BMW that will end soon.
BMW announced that they will be changing the carbon fibre driveshaft to the steel driveshafts because of the stricter emission regulations. Since the diameter of the carbon fibre driveshaft is bigger, it will be harder for them to fit in the new filter but the steel driveshaft is narrower and therefore, BMW has decided to bring back the steel driveshaft.
Some people were concern that the change would mean that the performance of the vehicle would change as well but according to BMW, it won’t so that should be a relief to the fans.
BMW also added that while the driveshaft would be heavier, they do plan to compensate it by fitting on a lighter flywheel or half shafts to even things out.