“With a fuel-injected car (which means “every car being manufactured today”), in a “normal” climate, there is no reason to warm up a car after starting it. The fuel injection system will compensate for a cold engine. In fact, starting the engine and immediately driving down the road actually helps reduce a car’s emissions. The car’s Catalytic Converter can’t do its job until it gets hot, and it gets hot faster if you are driving the car rather than letting it idle.”
More on Catalytic Converters in winter:
“The catalytic converter – the device that cleans pollutants from the vehicle exhaust – does not function at its peak until it reaches between 750° and 1500° F. The best way to warm the converter is to drive the vehicle. Idling emits more pollution if the catalytic converter is not working properly.
In winter conditions, emissions from idling vehicles are more than double the normal level immediately after a cold start. Warming up the engine means more than just the engine. The tires, transmission, wheel bearings and other moving parts also need to warm for the vehicle to perform well. Most of these parts do not warm until the vehicle is driven.”