By the way, what does the grey line indicate? Predicted battery percentage calculated by distance, elevation and rated efficiency?
You can see that it was off by quite a bit this morning (but I did have a phenomenal 184 Wh/mi average commute this morning)....
I believe it's the "original" prediction when you first plugged in the destination. This allows you to compare current performance vs. how it originally projected.
Occasionally this display can be a bit buggy (especially in absence of cell signal), but overall it's pretty useful. It takes into account elevation gain/loss, etc. on the way to your destination. It does not do well if you dramatically alter your wheel configuration (though there are now options to switch wheel configurations and that allows the estimates to work a bit better if you can select an appropriate one - people with massively wide wheels are out of luck though - predictions will always be optimistic). You'd think it wouldn't matter (since this screen does apparently to some extent take into account current efficiency), but it does.