In terms of perceived heat per energy usage, heated seats are the biggest win. At least in my ancient Volt I can get things pretty efficient by focusing only on seat heating over cabin heating. The trade-offs are a lot of passengers get confused by that and some of them distrust it because a vent isn't blasting a bunch of air at them (which is hugely inefficient; but was "cheap" when ICE had so much free waste heat). Also, none of the models today focus on rear passenger heated seats, that's still seen as too much of a "luxury car" thing, which is weird (and inefficient).
In the Volt it was a lot of fun to play these sorts of micro-efficiency games because getting to 40+ miles of range on an estimated 35 miles of range battery was always exciting.
(ETA: The number of times I wished I could entirely lock passengers out of HVAC controls was quite high. Seriously what is it with some people and their wish to have loud obnoxious fans blast 70+ degree heat at them in winter? While they are in their winter coats? For a five minute drive?)
In the Volt it was a lot of fun to play these sorts of micro-efficiency games because getting to 40+ miles of range on an estimated 35 miles of range battery was always exciting.
(ETA: The number of times I wished I could entirely lock passengers out of HVAC controls was quite high. Seriously what is it with some people and their wish to have loud obnoxious fans blast 70+ degree heat at them in winter? While they are in their winter coats? For a five minute drive?)