Learned something new relevant to the original question of this thread:
BMW engineers say:
Quote:
Modern direct injection diesel engines are now so efficient that the energy going into the coolant circuit and, therefore, to the heater is no longer always sufficient to meet the customer’s [heating] requirements. It has therefore become quite normal to fit cars with an additional electric heater providing such extra heat on up to 1,000 W of electrical energy.
To deliver such energy for additional heating, the engine has to develop up to 2,000 W -- since about twice the amount of mechanical energy is required to provide one watt of electrical energy. In all, therefore, such additional heating involves an increase in fuel consumption of up to one liter
source: http://www.greencarcongress.com/2009...-new-ther.html[/100 km].
|
So... with some diesels, using the heat can impose a significant MPG penalty... because of a dedicated electric heating element.
I have read anecdotal stories about the smart fortwo diesel that was sold in Canada having insufficient cabin heat in really cold (think -20 C and below) conditions.
The Toyota Echo sold here also had a beefy electrically heated element in the defrost circuit so you could start to clear the front glass before the engine warmed up. Not sure if it's still offered on the Yaris or other cars.
I have to say in the depths of winter, I am sometimes very thankful for the ~20% inefficiency of my gasoline engine and all the waste heat it produces!