My E90 335i is unpredictable. It has randomly failed in the following ways, only to correct itself upon restart: Loud buzzing from the speakers when I opened the rear door (engine not running) Misfire at speed (coil or spark plug was to blame but nothing was replaced and it hasn't occurred again) Wild throttle modulation on idle (without me touching the gas peddle). This occurred this morning and was accompanied by a delta sign with an arrow encircling it. Vent closure regardless of fan speed or vent setting Airconditioner compressor wouldn't engage (twice) The revving of the engine today and the coil failure upset me the most. I feel like I'm driving a Microsoft computer since I have to reboot it so often. This is an '09 with 25K miles.