I have stopped worrying about HV and EV modes and when to use them. I have a 66 mile commute each day and have played with all kinds of strategies eg: timing when I turn on various modes etc. Ultimately I began to realize that it doesn't make any difference to me at all. I simply get into the car each day and start my drive. At a certain point the EV runs out and it doesn't bother me in the least. Actually, sometimes I notice that I get a little bit more EV here and there as I brake. I have seen no difference in this way of driving than in meticulously timing my EV and HV modes so that I cruise back home with exactly 1 mile of EV remaining. Actually, the car is so smooth on the freeway that even in the last 15 miles or so without EV, the revving rarely bothers me.