Not a cigarette lighter, a power outlet. Clip from the manual:
"Power is available whenever the vehicle is considered "awake". The vehicle may be awake for many reasons. For example, when using features such as Summon, or when features such as Cabin Overheat Protection, Keep Climate On, Dog Mode, Sentry Mode, etc. are enabled. The vehicle is also awake whenever the 12V battery is being charged or is in use, during HV charging, when the vehicle is communicating with the mobile app, etc. Leaving an accessory plugged in does not deplete the 12V battery"