The car engine works in all kinds of conditions, even without preheating. However, there are good reasons for preheating your car in the winter and when temperatures drop under zero: it reduces engine wear and fuel consumption at ignition.

If you start your car in very cold temperatures without preheating, you will use a decilitre or two of excess fuel. In addition, during the first kilometres after ignition, fuel consumption may increase by as much as 40–50 per cent. In one year, the savings achieved by preheating the car can easily exceed one hundred euros.

Driving is also more comfortable and safer if the car interior heats up more quickly. A separate electric fan heater in the footwell, for example, offers added comfort. Heating the car dries up the interior and removes frost and ice from the windows.

Heat the engine sufficiently, without overdoing it

It is always a good idea to preheat the engine when the outdoor temperature drops under +5 °C. However, do not go to extremes:

  1. Half an hour is enough when the temperature is around zero.
  2. When the temperature drops under -10 °C, opt for 1 hour.
  3. At temperatures around -20 °C, go for 2 hours.

Heating your car with a block, inline or radiation heater

The first block heaters appeared on the Finnish market in the 1950s. Today, both electric and fuel-powered auxiliary heaters are installed in cars. Electric cars such as Teslas and the Nissan Leaf even feature air source heat pumps.

Back in the day, a block heater simply meant a heating resistor installed in the car engine. As engine blocks became more cramped, and engine manufacturing technology developed, inline heaters attached to the radiator hose emerged. Both block and inline heaters heat the car's coolant, efficiently heating the engine and later the car interior. Both are available for nearly all car models.

Other options include radiation heaters, which heat the motor oil instead of the coolant. If we only consider the engine's durability, it's more important to preheat the oil than the coolant, which heats up quite quickly in any case.

For various conditions: fuel-powered auxiliary heaters

Some of the best known fuel-powered auxiliary heater brands include Webasto and Eberspächer. They can be used for heating even when no electricity is available and can be scheduled with a mobile phone application, for example. Moreover, fuel-powered auxiliary heaters are fast: they require no more than half an hour, even at extremely cold temperatures. In half an hour, these heaters consume around three decilitres of petrol or diesel.

The disadvantage of fuel-powered heaters is that they strain the battery. Ensure the battery is charged either with a battery charger‍ or by driving the car for at least as long as the heater was used.