Today I drove my Prius Plug-in from my home almost to the highway in EV mode. When about one minute from the highway, I pushed the PWR mode button twice, on and off, and the ice came on for warmup. All the green symbols above the speedometer were cleared. I then again pressed ECO to bring back that mode. I believe the vehicle was in what I think of as blended HV mode. This mode blends the extra battery capacity of the Plug in with the ICE. After a 40 mile trip, the available EV miles dropped from 13.9 to 1.2, and the trip meter registered 76 MPG. I went up and down a serious hill which probably reduced the mileage. I believe there are two HV modes. The blended HV mode I used today, and a normal HV mode that operates like a standard Prius and attempts to not deplete available EV miles, saving them for later city driving. I think the normal HV mode is entered by toggling the EV/HV button until the green HV symbol appears above the speedometer next to the ECO symbol. I haven't used the PWR mode yet, but I am guessing it will blend because it removed the green HV symbol.