Pass on it, totaly pointless here in the UK as we rarely get below -5c
I agree that there wouldn'tr be a return in the UK on the £1k id3 heat pump investment, versus spending on electricity.
it's unclear what climate you would need to live in for them to be energy efficient though ? - the tesla one, which is not c02 like the vw, was less efficient at low temperatures, so the default installation in the Y maybe undesirable in the scandinavian countries, and paradoxically, most beneficial in moderates like the UK
pre-conditioning looking at tesla heat pump video seems that at -7c(-14 windchill) the heatpump version is taking more W/mile, so heat-pump probably wouldn't be sufficiently powerful/versatile for use as a battery heating solution alone : https://www.youtube.com/watch?v=MsSxpq-xUMY
from https://www.reddit.com/r/teslamotors/comments/lhx1ox/2021_model_3_heat_pump_cant_handle_the_cold/
After reading an article on id3 heatpumps https://www.goingelectric.de/forum/viewtopic.php?f=393&t=58265&start=50
if you are able to pre-warm the car (daytime rates - yes) their benefit may not be so great, unless you live up North.