This is really interesting. Mostly because it takes me back to a decision I made looking at getting a LEAF 5 or so years ago. EVs are known to lose a considerable chunk of range when the temperature drops horribly. IT also loses range when the heating is on, have both (which isn’t unreasonable) and the range cad drop by nearly 50%, which is about where you are.
Here’s the clincher, if you have a summer range of 300 miles, your driving is mostly local or your commute is less than 50 miles each way, you end up finding yourself charging more often but still able to do the trips you were doing. If, however, your vehicle does 110 miles and you’re used to having to charge either daily or every other day, you now will go from noticing the range difference to worrying about it. A drop from 300 to 180-200 isn’t great but you can live with it, a drop from 110 to 70 is worrying and means you’re spending more time connected to a cable than moving. That is a problem.
So, if you’re looking for an EV (as I’m beginning to look for) then you need to bear in mind what the winter range might be as well as the summer nice numbers. I wouldn’t go for anything under 50kWh, possibly not 60 if the vehicle is big or the range is less than 200 miles.
https://ev-database.uk is a really good resource for actual driving ranges, although they have been a little harsh on some. They’ll show you the winter and summer ranges and different speeds. According to their figures, the Vivaro should do 75 miles on the highway in cold weather, 95 in warm. I’d say there might be some driving style changes to that number but the drop does seem a little generous on their stats.