Heat pump
An efficient climate system that moves heat instead of generating it. In winter it can save a good chunk of the range that cold eats.
Heating the cabin with an electric resistance is like using a hair dryer: it burns a lot. A heat pump, instead, moves heat from outside in, spending far less for the same comfort.
The result is more range when it's cold. In temperate or tropical climates the benefit thins out, so its value depends a lot on where you live.