If you are above 40 miles per hour, the trick I have found is to not back of completely on the accelerator when you are up to speed and reducing power.

If you let it go all the way off, the computer will try to put you in EV mode, which will only be transient because you are above the maximum speed for MG1 with the ICE not turning. The result is that you are in fuel-cut (ICE turning but not burning with traction motor[MG2] on) until you put the accelerator back in sufficiently for the ICE to start, which in turn shuts down the traction motor at those speeds.

IF you back down the accelerator to less than a full off position, the computer sometimes thinks this is merely a power reduction and will set the MG1 to MG2 relationship for a very high ICE to axle gear ratio (a sort of overdrive). You can tell when this happens because the MPG will enter the 40-55 MPG range and you can "feel" the slowing of the ICE along with a feeling of the car going quieter. The speedo center display will show ICE running and also a "battery to wheels" indication which is a little misleading as it only shows that the MG1 to MG2 loop is operating in some mode other than open loop.

It is the ignorant among us that will eventually destroy us all.