This is showing you just why short journeys in the cold will return such low efficiency figures - the car is spending a lot of energy warming itself up.
For comparison, I made a round trip journey of 60 miles yesterday, finishing up with an average consumption of 3.4miles/kWh (cross country motoring).
The day before, I left home with an 80% charge, range estimated at 180 miles. One mile on (up a long steep climb), it was down to 140. A further mile (on the flat) and it was back over 170. Don’t read too much into the early part of a journey.
…which is much closer to what you will see whenever you stop on a longer journey (for lights etc).
EDIT: I hope you will stick with it. My experience suggests at this time of year 3-3.5 miles/kWh on a good run, comfortably over 4 in summer.