Anecdotal, but my personal experience with an Ioniq 5 in -28C increased the power consumption by about 50% over summer driving. My test was about 42 km, done with comfortable, driver-only cabin heat on a flat highway with no wind.
Average highway consumption is about 20 kWh/100km, that test was 29.3 kWh/100km.
Saying that, an EV is quite practical in Saskatchewan, Canada. Charging is finally getting to a point where that extreme winter range limitation is less of an issue. Having a second ICE vehicle does take the pressure off if one absolutely has to travel when it’s that cold out though.
I love it. It’s a 2023 model, so the new shape. It’s the vehicle of choice for nearly all trips we take over a '20 Subaru Outback. Charging is slowly expanding in the province so it’s becoming even easier to plan drives. Really the biggest frustration is our biggest city only has 50 kW fast charging.