Did my regular trip to my daughters yesterday and thought I'd try an experiment. The journey is 80 miles one way, mainly dual carriageway no queuing in traffic. On the way there with acc on 65mph i got 3.8m/kWh average. On return journey i used acc set at 60mph and got 4.5m/kWh average. I know it's not very scientific but I was very surprised it made that a big difference to the range. It was a bit boring at steady 60mph, but useful to know when I do the journey in winter.