• Idling for more than 10 seconds burns more fuel than turning your engine off and restarting it again. Driving warms up your vehicle twice as quickly as idling, reducing fuel consumption and greenhouse gas emissions.
• Idling is not an effective way to warm up your vehicle.  Not only does your engine need to be warmed up but so do your tires, transmission, wheel bearings and other moving parts.  The best way to warm up your vehicle is to drive it while avoiding high speeds and rapid acceleration for the first 5 km.
• The catalytic converter in your vehicle,  the device that cleans pollutants from your vehicle, does not function at its peak efficiency until it reaches a temperature between 400 and 800 degrees Celsius.  The best way to warm up your catalytic converter is to drive your vehicle.
• Idling can damage your engine because your vehicle is not at its peak operating temperature.  As a result, fuel combustion is incomplete which leaves fuel residues that condense along the cylinder walls contaminating the oil and damaging the engine components.
• Restarting your car numerous times has little impact on your vehicle and its engine components like the battery and starter motor.  It is estimated that the component wear caused by restarting your engine is $10 per year.  This amount will easily be recovered in fuel savings from reduced idling.

Source: City of Calgary Environmental Management