That's a small electric engine heater that plugs in to your home's wiring via a regular, 120 volt AC plug, at night. It's almost required equipment for diesel engines in frigid climates. But it can be used on regular gasoline engines, too. And for less than a hundred dollars, you can be virtually guaranteed that your car will start, even on the coldest, butt-freezes-to-the-driver's-seat mornings. A side benefit of this is that you'll have instant heat in the morning.

Actually, that may be the greatest benefit! One note of caution: If you do get a block heater, try to remember not to drive off with your car still plugged into your house.