I've yet to use my Tesla in the dire cold; I'm told there is a for-purpose defrost mode which is not the same as the battery conditioning or the normal HVAC control. My understanding is the defrost mode runs all heating methods/elements at 100% to accelerate melting all the ice/frost off any exposed surface. If the internet is to be believed, it can get the job done inside of 15 minutes.
For whatever it's worth, I have the Model Y which uses a heatpump rather than an electro-resistive element heater. As such, if the temperature outside is above freezing, cabin heat can be very power efficient. Once the temp is close enough to freeze, the pump functions as a electric element heater just from the motion of the pump itself. IIRC the Model Y is the only model in the Tesla lineup with a heatpump.
As a general rule, Tesla encourages owners to leave their cars plugged in at all times while at home. Any preconditioning will require power, and as such you'd prefer that power be drawn from the wall rather than draining your battery.
For whatever it's worth, I have the Model Y which uses a heatpump rather than an electro-resistive element heater. As such, if the temperature outside is above freezing, cabin heat can be very power efficient. Once the temp is close enough to freeze, the pump functions as a electric element heater just from the motion of the pump itself. IIRC the Model Y is the only model in the Tesla lineup with a heatpump.
As a general rule, Tesla encourages owners to leave their cars plugged in at all times while at home. Any preconditioning will require power, and as such you'd prefer that power be drawn from the wall rather than draining your battery.