Odd highlighting on SatNav

[Brockysuperb]

We've had the MIB3 infotainment updated - hugely better in terms of reboots, and no random SOS calls. But on the Sat Nav a new feature has appeared which we noticed on a trip through France. Some of the time an a area round our route (which changes, and isn't always parallel to our route ) is highlighted - as the pictures show. Anyone knows what this is or what it means please - not in our manual anyway, and it didn't do it before so I suspect it's new. 

[Gus755]

That shows the distance that you can travel until you are out of charge and possibly petrol as well, although I'm not sure about the petrol.

[Brockysuperb]

Thanks...sort of makes sense. But it's wierd...it means we can travel further in one directiin than the other? (top picture).