I'm trying to get clear on how to recognize when a BMW i3 has the optional extra of 'Auxiliary Cabin Heating System' and also how to use it.

I've read lots that describes how it works, i.e. a heat pump, and why it's such a good idea to have this in colder climates such as Scotland. I've had a test drive in the BMW i3 with the system as an optional extra and was told the only way to tell was in the software menus.

I'm not totally convinced by this response. I think there must be physical signs to look for to identify the vehicle has a heat pump instead of an electrical heater.

On the how to use it side, I'm unclear if when you simply put the cabin heating on it uses the heat pump, or if you need to select 'Auxiliary Heating System' via the software menus? Does having the 'Auxiliary Cabin Heating System' mean the car doesn't have the more power hungry electrical cabin heater?