Traditionally, Scandinavian countries would use electric block heaters (like an electric kettle element, fitted via the casting core plug holes) to keep the engine/coolant up to a temperature that would make starting easier, after a vehicle was shut down overnight. Sometimes, if a block heater was not an OEM option, a similar heater could be inserted in one of the radiator hoses.
Mains electricity is the only sensible way to power these.
I think I recall, from way back (1970/80s) that some diesel trucks would be left to idle while the drivers rested, or during loading/u8nloading, as some old diesels could be a bitch to start below certain temperatures, necessitating ether injections or flame starters.
In more modern times, and with the vastly increased popularity of diesel engines in passenger cars (in Europe at least) the accent has also fallen on taking the chill off the passenger compartment using so-called 'auxiliary heaters'
The inherent improved thermal efficiency of the diesel cycle, coupled with pushes to increase the fuel conversion efficiency of diesel engines, has lead to customer complaints regarding the slow build up of heating in the passenger compartment.
As a result, products that burn fuel, or utilise electrical power to generate heat have been incorporated (or are OEM options) in many of the latest European diesel cars.
Check companies Webasto (fuel-fired heaters) and BERU (PTC electrical heaters) for information on the way these are incorporated into vehicle systems.
Some vehicle OEMs will also have engine control systems which automatically switch on electrical loads when ambient temperatures are low, in order to load the alternator. This increases the power consumed from the engine and thus the waste heat generated; the knock-on from this is that the coolant temperature rises a little quicker than it otherwise would. A waste of fuel.
If a diesel system is well designed for use in a cold territory (battery, starter motor choice, oil type, fuel mapping, etc, etc.) then, these days, unless you are living in persistant temperatures of less than, say -15ºC, a reasonably maintained vehicle will function well. Whether the operator/passengers like the cabin temperature characteristics is another matter.
Windscreen wiper heaters are trivial uses, compared to the engine and vehicle systems heaters.
Bill
