I've been using a small ceramic ac heater in my cars for years. Plug it into a digital timer, comes on M-F only. 1500w for about 40min before I leave for work gets the inside nice and warm. I park outside in Buffalo. It won't melt a foot of snow but a plastic shovel pushes it off without scraping. Just got my 08 prius, I unplug it while walking around with a brush, jump in and hit recirculate for 5min. Before the windows fog the ICE is warm.
Ya know what's cool? Just about every production EV from the 90's had this built in. You could heat or cool the interior at a set time each day for the ride into or home from work. And the best part is that the preconditioning would operate from "shore power" and would not use any battery capacity. So you start off with the cabin at the proper temp, and don't need to use extra battery power for that task. We'll see more and more of this when we finally get BACK to plug-in cars!
