S1b charging values

It's a common rule of thumb that, while perfoming the first cold ignition of the Yaris Hybrid, you can push up to the 2nd mark of the ECO level without draining the battery.

This seems not to be always the case.
I've observed that at a low SOC level (battery indicator at 4 bars), you can push as much as the half of the ECO zone, and still charge the battery.

Look at this chart, where S1 starts with SOC > 50%.
As soon as the Hybrid System Indicator raises over the second mark, Battery Current goes positive, thus draining power from the battery to push the car.
This is the commonly observed behavior.

Now, look at this chart, where S1 starts with SOC < 50% (4 bars on the dashboard).

Even going with the power meter at half of the ECO scale, current remains negative (flowing from the motor/generator to the battery pack).

So, where is this additional current coming from?
Engine RPM are the same in both cases:

Let's check Load and Fuel Flow:

Same values in both scenarios also.
This scenario has been investigated on a Hybrid Synergy Forum thread.

Highway engine speed and consumption

Here is a chart of several highway trips pasted together, to have a wide number of samples.
All trips were back and forth on the same road, so altitude differences were evened out.
Values are significant after 75 km/h, when you can't have electric engine running alone, and after that, more samples lead to more consistent results.