When I drove my MG5 I always put it in ECO. I just got into the habit of changing it every time I got in - to my mind it gave better range, and no discernible loss of performance. Driving on motorway at 70 will hurt the range, for sure. If you want to get the most between stops then stick to 60mph. At the end of the day you'll get there quicker at 70 but have to charge longer, at 60 you'll get there slower but will have to charge up less, so swings and roundabouts. In the end I was getting near 5miles/kWh in the summer once I'd learnt to drive it economically ... also worth considering turning regen down as low as possible, sounds wrong but the car will coast better if regen is low and that, it turns out, gives better range when cruising on motorway ... well in theory at least