300miles is the same rating as a Leaf being 123miles, i.e. Bollocks. 250 is more reasonable, it doesn't take such a massive hit at motorway speeds as it's pretty aerodynamic. Maybe you'd get less than 250 round town (in fact I am confident you would) but if you're averaging 15mph round town even 200 miles range is over 13 hours use!They're saying 220 miles rather than 300? That's some drop in percentage terms?
What kind of speed was that on the M23?You get a lot more regen around town, and the car is most efficient below 50mph. Mine's giving a "typical" range of 220 from a 90% charge. Trip down the M23 today gave average of 360wh/m, which is almost spot on for 220miles range when you factor in the anti-brick buffer.