Economy driving zone
 

2012 Highlander Hybrid

Question. Left gauge shows "economy driving zone" and manual recommends to "stay within" it for most efficient driving.
That's cool, but why do I have sometimes 2 bars lit in that zone, sometimes 3, or 4?
Also, what is "charge" area for? It does not seam to be ever used....
Same entire gauge shows "hybrid system output in kwt".
Is that for hybrid motors ONLY or for entire V6 coupled with 2 motors or one motor? 200 kwt for electric only is a lot of ponies, you know.

Thank you