Why don't electric cars come with a tiny kerosene cabin heater as standard? A small heater would take up little space or weight, could be easily refueled at home so not need a detour to a petrol station, and be much more cost effective than adding extra batteries just to provide cabin heat. Sure, it's not zero-emission, but the efficiency of a kerosene heater can be pretty good (much better than an internal combustion engine) and it might go a long way to increase the usefulness on cold days.