Looks like a 25 to 50% loss of battery life. In a nissan leaf, this puts you into the 50 mile or less range from what I understand. If you have a Tesla, which has a much beefier battery your range is much more, but still depleted.
I read an article that said the greater concern for EV drivers in the severe cold was not the reduced range but the loss of power when charging. Apparently the grid is lost quite frequently in those cold storms.
But that all being said, Doesn't -25C gel diesel? Then I realized you wrote C, no F. What first world cities get -25C on a regular basis? Just asking.
Being a greenie I guess (well, earth conscious maybe?) I am less concerned about cars and the polution. New gas engines are really dropping the emission levels to next to nothing. And as I noted before the diesel electric might just be the stop gap for new car manufacturing until someone truly makes a decent battery.
I think power generation is the real issue now. Coal has got to go. Same with Fracking. But also, the US has to get tough on other countries that don't step up to the clean air plate and by that virtue can produce product at a much lower rate.