Fascinating! I had always thought there was a surplus of heat considering heat was the main thing produced by ICE cars. What I had not considered was the efficiency (or lack there of) of directing that heat. What you say makes sense to me.
On human sensibility scales, yes, the ICE always seems to be putting out surplus heat. But watching my Prius' engine coolant temperature on an OBDII-port monitor (I have a ScanGauge, but many newer-better-cheaper options are available), it wants to maintain 195F. It does that easily on flat highways in moderate weather, but can dip significantly on downhill glides or slow city traffic, and even more in winter or when using cabin heat. That means more fuel burned the next time it goes ICE-On for some other reason, trying to get back up to 195F. But it won't run solely to warm itself up, without any other reason to operate, above 103F in ECO mode, or somewhat higher in Normal mode.
