Letting the car consume a small amount of constant electricity to keep the battery above freezing is thankfully not very expensive compared to a standard space heater (usually 1.5kW at 720 hours a month, costing $150 a month in Seattle).

Defrosting and toasting the cabin to 92F in freezing conditions usually burns about 1.2kWh to 3kWh while plugged in, but that is just a few tens of cents (or free depending on the charger) to get nearly instantly toasty and ready to drive.