Operating at -40 is one thing, charging at -40 is another.

I have no idea how true this is, but the press releases claimed that both most of the capacity is retained down to -40 and that the charging speed is proportionally retain down to -40, and that this is the meaning of the operational range.

Right, good to know.

When you're at a charger you can easily spare the 3-4% of battery capacity it takes to heat the pack by 40C. Less if you use a heat pump.

How many people let their ICE engine block get that cold?

For -40, the anecdote for combustion engines used to be that in Siberia you turn on the car's engine in november and off in march.

For -20 though, it can happen each year in 4 season temperate climates and north of that.

i would have imagined that charging at -40 is easier than operating at -40.