I have a 2010 528i without a Logic 7 no Navigation or CD changer. When I get into the car and put the key in I can here everything power up. I hear no noise over the stereo at no volume and all sources. Then I turn the engine on and the sound of data transfer like electrical feedback starts in the background. It is intermittent like "zzz zzzzzzzz zzzz zzzzzz zzzz" it doesn't increase with volume and can be heard with mute on or with any input. It goes away when I turn the engine off. I guess the best description would be like hearing a CD player searching for a track. I wonder if it is feedback from an engine part since it only happens when the engine turns on? It is on all interior speakers. Any help would be appreciated as BMW isn't helping much.