Yesterday it was -16'C (about 4'F) all night and in morning. My 2018 wagon started-up no problem and engine reached operating temp in about 5 minutes. I have the electrically heated front windshield, but could not see any difference over 'normal' windshield for defrosting. Love the heated outside mirrors though.
Also noticed wires going to the front washer jets under the hood. Seems they have some sort of heater that works with the electrical wind shield. Nothing in the owner's manual about it.
HAPPY HOLIDAYS TO ALL, Please stay healthy and safe!!