BMW Questions? Ask a BMW Repair Expert for Answers.
There are several different types of engine heaters available. The specific one you choose will depend on the make and model of your vehicle as well as your mechanical ability. The simplest kind of engine heater replaces the oil dipstick. A slightly more complicated type of heater splices into the upper radiator hose. It can be installed in a matter of minutes with a screwdriver. The most effective engine block heaters replace a drain plug on the bottom of the engine block
depending on the type of heater, the cable will need routing out of the engine bay and securing to an access point so you can easily plug it into the mains, the location of this plug will be up to you, but as long as the cable is secure with cable ties and not touching rotating or hot parts then it'll be fine
I'd also suggest using an automatic outlet timer, because it is only necessary to heat the engine for about 2 hours before driving.