Does PiP coast differently from a Gen III?

In other words, when going down a hill, if you step on the throttle just enough so that the dashboard display shows neither regeneration nor usage, then you are essentially coasting in Neutral, neither generating nor using electricity. But if you get above about 62mph in EV mode, the ICE will start turning to protect the Power Split Device. I am not sure if in this case any gasoline is being used, or if the motor-generator is just spinning the ICE without compression.