I agree. Physics seems to say that isn't going to happen with any degree of efficiency. Keeping windows free of frost in a vehicle is a necessity, apart from keeping the passengers alive and comfortable. FF burning results in so much waste energy, that function is a free gift. For an electric, whole different story. Then the dilemma of keeping the batteries heated at minus 25 or colder. If battery power is expected to heat the batteries, the system efficiency is gone, and standby capacity would probably be in the range of a day or two before full depletion. Obviously an active heating system plugged into the grid would be much more efficient, but still very costly, and needing standalone backup on board. As for cabin heating, I believe a propane or natural gas auxiliary system would be far more efficient. Charcoal might be pressed into service.
Granted, these challenges become less critical the further south you go, but windows have to be frost free, and pushing tires through snow uses way more power.
Given that the north American electrical grid is powered generally by coal and natural gas, crunching the numbers leaving aside cabin and battery heating it soon becomes clear it's more efficient to just burn the natural gas in a conventional vehicle. The real world efficiency gains are to be had by reducing curb weight, wind resistance, and rolling resistance. Easily enough gains are available there that the president could, with a stroke of a pen, mandate efficient vehicles to the degree that the US would cease to import foreign oil.