I have just acquired a 2013 G13 (no nav, sedan). When I play music from a flash drive through the USB with the ignition button in the ACC mode (i.e. the engine is not running), the music cuts out after 2 hours and the car fully goes back to sleep. I cannot find a mention of this timed shut off in the handbook, but it does mention that prolonged use in the ACC mode will drain the battery. In my case this cannot be the problem as the car starts fine after the shutdown and the battery is less than 2 years old. Has anyone else come across this, or do I have a special edition G37?