What factors affect engagement of EV mode?

i have a part wer i have a sharp left turn fallowed by a down hill drop (nearly allwes i end it at 8 bars)
i turn on EV mode after the turn so wen i get to the drop thers room in the batter for all the power from the drop

unless the Prius computer uses position and diraction to know wat is the best SOC at the moment ther are times wen the driver knowes best

 

The computer "knows" that 100% of the power used to propel the car comes from burning gas in the internal combustion engine.

It therefore "knows" that any substantial gains you have when going downhill will eventually be offset up when going back up the hill again later.

I prefer to concentrate on driving safely and not obsessing over trying to squeeze out the last tenth of a mile out of a gallon of gas........and prefer that drivers around me do that too.

While it looks really good on the display in the short term, in the long run it really doesn't make much difference.

 

You can manage a wack electric-only propulsion without ever touching the EV button. Without even trying the car will put you in it, frequently. With a little effort you can up that frequency, even to the point of running the battery down, if you care to. That's more than enough for me.