I am currently sitting far up in nothern Norway and I am early for an appointment.
So I figured I'd wait in the car for the time to pass. But since it's currently -15°C outside: I need to have heating on. My car (a Volvo V40 D2 - 2013) is fitted with a heating unit that warms the engine and cabin using diesel without having the actual engine running.
The engine consumes 0.5 l/h when warm (0.9 l/h cold). The numbers for the pre-heater I got no idea about.
So what is more efficient and economically best to use while waiting? The pre-heater or the engine itself?