It's not just the batteries: heating the cabin takes considerable energy in -20C, but but the heat is "free" on fuel-burning engines.

Hopefully there will be more data available and released in the future, as Tesla and Nissan Leaf have been the best-selling cars in Norway for multiple years in a row.

For anecdata, an Uber driver with a Nissan Leaf told me recently that range on very cold days is about half of the summer range.