With over 56 years in the frozen north, I have used just about every method of warming vehicles out there. Circulating tank heaters are the quickest 750-2000 watts. Block heaters are cheaper to operate but much slower to heat things up. They are usually around 500 watts. I have used actual Head- bolt heaters and dipstick heaters, both fairly worthless. I have used heat lamps, electric blankets, Reddy heaters and weed burners. I have drained the oil and anti-freeze and have brought them in the house to keep warm, along with the battery. I have heated the wheel bearings with a torch, just to get them to turn. Fun, fun, fun!
Modern vehicles start much better and lubricants have improved immensely and help a lot with cold weather starting.