Electric cars have been tested in environments to -17 deg. F. without a substantial reduction in performance. They are probably more reliable than regular cars at that temperature.
As for regular cars, synthetic motor oil and block heaters have rendered starting reliable to -35 and colder. Once running, I have had very few problems in the last 100,000 miles, with a variety of vehicles from a 1975 full sized chevy van (350 V8, 4 bbl carb) to a 1990 Dodge caravan (fuel injected 3.3 liter).
Did the electrics make the 260 mile round trip to the next major town at -30, busting snow drifts and keeping the cabin temperature above freezing, and do it in the roughly 5 hours a gasoline vehicle will, with enough 'fuel' left to keep the lights on (so you don't get hit by another vehicle and can be seen) and keep the occupants warm for a few hours if you end up in the ditch?
Or were they tested in a controlled environment?
Otherwise, they are a deathtrap.
Many of the smaller cars cannot handle the road conditions alone for lack of ground clearance, and they lack the mass (which translates to momentum) to bust drifts.