Most cars in Alaska, Montana, Minnesota or Maine -- in short, any U.S. state bordering Canada -- are equipped with block heaters. When you live in a region where the temperature can drop below -30C (approximately -25F), a block heater is a necessity if you want your car to start in the morning.
A block heater warms the radiator and the engine coolant contained therein, as well as the entire engine compartment. At temperatures below -30C, engine antifreeze begins to congeal, restricting the flow of water though the coolant system. This means that the engine will take longer to reach peak operating temperature, and that your car's passenger compartment heater will blow frigid air for a few minutes longer each time you start your car. Because your engine is operating at a more ideal temperature, fuel economy is improved up to 10 per cent instead of cold starting your car. Sometimes, your car won't even start at all without the block heater working. Trust me, I know.