Yes I think it is later models that use the pump to circulate coolant for a certain period after shut down to "eliminate hot spots" in the engine. That's actually an interesting idea if someone is dealing with such an issue. I like that with everything off I can make the pump run with the key on position 2 and the climate control settings calling for heat.

Someone had also mentioned using the pump after a coolant change/system service to help remove air from the system without having to run the engine if that is an issue or a concern at the time. Makes me wonder if this electric coolant pump could get you to the next exit if you're dealing with fan issues or a failing main water pump, a working temp gauge of course, and the heater on max to circulate coolant to help dissipate heat. Keeping this pump in the system just might have other uses on the W123 beyond extra heat while idling even if it has to be run on demand. Having that much control of the pump might even be an advantage. On other systems it mostly runs off of sensors. If it's $30 every 10 years I will likely always maintain an auxiliary coolant pump.