Good to know. I'm not running snow tires this year but I have allot of tread on my all seasons about 90% seeing as I drive allot into a snow belt area its a bit of a gamble. For engine heating I put a set of plug in seat warmers in to keep me and my passenger warm. This way I avoid running the heater and my car heats up up about 5 min of driving. I keep the tire pressure at normal rates as again snow grip is important. However I am seeing mid to high 600km per tank again so I must be doing something right lol.
For the frost issue I just scrape away at the windshield and put the rear defroster on I noticed that in some cases an open window dose not fog up the windshield so on some ocasions I will drive with the driver and passenger windows open a bit to help de-fog the window. Good gloves help with the cold lol, and being a bit crazy too
.