The Fusion Energi can provide heat without the ICE on, but it will cost you a fair amount of electrons from the battery. The Energi has a 5kW resistance heater (not a heat pump). Thus at least initially, it starts out at 5kW draw then tapers down as the temp rises. It will typically show a ~4-5 mile drop on the estimated EV range left when you turn on the heater or defroster.
