nyceshirtz — I believe that what you say about the TCH and ScanGauge is correct, and that you are correctly interpreting the TCH's operation. Quite why the TCH sometimes does not go into pure-EV mode at low speeds, when everything seems to be right for it to do so, is not known to me. The car has a mind of its own (or at least its ECUs do)! I'm sure there's a good reason, known only to Toyota.

I'll have a look at the question of open-loop operation when coasting at speeds above 70 miles per hour (~112 km/h). I thought that the ICE did go open-loop even at these speeds. Certainly the ICE must continue to spin, either in open-loop, fuel-cut mode (using MG1), or else continue to burn some fuel (closed-loop). If it reads closed-loop, it's burning fuel, that's for sure.

Stan