Heat pumps are mostly useless when it is minus -20 C. Diesel heater is the most practical solution. Sodium or LMFP batteries will help, but even with them the range reduction in winter due to the need for heating and increased drag from cold air is just too great.
diesel fuel itself needs to be heated at -20 C and below. I used to have a diesel car which would start itself up periodically when its fuel temp was getting close to -20 C, just to warm up the tank & pipes.
Ok i get that some people really do need to deal with extreme temperatures regularly, but it totally misses the point when discussing a mass market car like the Corolla. It’s like asking business casual footware to be equipped with crampons for when you need to walk up a glacier.
> Heat pumps are mostly useless when it is minus -20 C.
Two-thirds of households in Norway are heated by heat-pump, so I don't think that can be true.