Up to about 100Km/h speed on the flat the car will run ev, but faster than that, or uphill, the ICE will run.
Once charge runs out the car will cycle between ev and ICE as you describe, unless you intervene.
CHRG mode starts the ICE and runs it at it's most economical steady rpm to turn the generator which will then power the car, so CHRG back up to 70%, then switch back to ev.
In SAVE mode you are mostly powering the car with the full rev range of the ICE, which is less economical than CHRG, but of course there are times when you want to SAVE, say, 10Km of charge, for ev driving through your destination town for instance.
Out of town run in B0 and coast when possible, but increase the B setting to regenerate on steeper hills, or gently brake which also regens - but not too hard or you will engage the disc brakes.
In stop-start conditions in town use B5 to brake, or gentle use of the foot pedal.
