Yes the one on the steering wheel when you press the button the map comes up with a white driving range and as you battery gets lower the white spot get smile as long as you keep your changing point inside the white spot you will get to the charging point when you slowdown the white spot get bigger that's why this has saved when a charging point is not working
I'm not overly keen on it being a crow-flies range rather than by road. The Leaf is still ground-bound I believe! I can recall being in York and the range button indicated I could get to somewhere near Cambridge ...
I have never left is set. Only switched it on for one-off checks. I'll see how it works but my concern is that it is "as the crow flies" as @BlackLeaf has mentioned. I also assume it is based upon the range as predicted by the Guessometer.
Yesterday I took a trip which requires a charge but I took it slightly too early on the outbound leg. To get an idea of the amount of top-up I would need to get home I set the sat-nav for home, not because I needed directions but to get an idea of the true distance. To my surprise it reported that I had a 52 mile journey (ECO) and GOM was showing 62 miles. Battery percentage was also about 62% so I know that it was achievable. I left it on and periodically compared the two as I got closer to home. With a couple of hills I dropped to 6 miles difference a couple of times but arrived home with 9% battery left. Had I not checked I would have stopped for an unnecessary charge.