I've ony had my TCH for 2 1/2 days now, but I did notice that the ICE had started a few times when I was making a turn. I think it all depends on the turn that you are making. Whether its uphill or downhill, if you are accellerating or just coasting.

What I have noticed is that you can let up off the gas pedal on a flat road when the ICE is on to shut it off and then maintain that speed in ev mode only.

One other thing that I've seen is that there is a delay of about 1 sec when the ICE comes on and the MFD shows that it has done so.