You're right that the ICE can essentially directly drive the wheels. Take a look at the model, and think of the outer gear (connected to MG2) directly powering

You're right that the ICE can essentially directly drive the wheels. Take a look at the model, and think of the outer gear (connected to MG2) directly powering the wheels. Then try setting the ICE to near max, and MG2 to about the same level, so the grey line is horizontal. That should simplify the visualization. See how the ICE pulling the planetary gears around directly pulls the large gear as well? Once you grok that, you should be able to see that even if you vary the MG2 slider, the ICE is still providing torque to that outer gear.