I have a 2015 435i Grand coupe with the m performance package. I went in last month and had the oil changed, ever sense then I've had a whining noise coming from the alternator area. It sounds like an electrical load if you will, I've replaced 4 alternators, 3 belts, 2 tentioners, 3 pullies, and 2 ac compressors all various companies. Nothing helps, nothing makes it any less annoying. It's so irritating I can't even drive the car anymore. It's been to 4 different shops over the last months time and no one can tell me what it is, where it's coming from or why it's started. All I hear is that it's normal or not a big deal. I know this is not normal, as I work in a shop and had another 2015 435i come in last week and that engine sounded absolutely perfect. Anyone have any advice or tips? Any help would be appreciated im going absolutely nuts with this car and am extremely ready to just sell it at this point.