The Model S and X have a dedicated battery warmer, the Model 3 does not as a cost cutting measure (it uses the motor windings to heat the coolant loop, but it appears this solution, while clever, is inadequate).
I kinda wish my ICE car would crank everything up while engine-braking down a hill to reduce brake and fuel use.
It shouldn’t be that expensive...
but in order to warm up the very large battery pack, on a cold morning you need to turn the car on (well) before you start driving to have it warm enough for full regen.
My 15 year old Golf does and engine braking is why I've still got the original brake pads after 180K miles.