Originally Posted by equipmentjunkie

I'll just add some clarification to 79Mercy's response. Your 240D has a naturally aspirated engine and cooling down is not necessary. Cooling down periods are critical on turbocharged engines. Letting the engine idle for a short period of time prevents coking of the oil in the turbo bearings.

When I bought my naturally aspirated E300D, I had to relearn my shutdown procedure after driving turbo diesels for over 10 years.