Is there a difference between full EV mode and the early HV mode where you are in EV(left half of the indicator on the HSI screen)? Aren't you in full electric in both situations? If so, then why would you need to manually toggle between the two modes?
HV mode will only let you use a small range of the battery making it behave like the regular hybrid Prius. This means at some point, it won't let you drain the battery anymore to travel further on purely EV miles even if you have plenty of energy in the battery. EV mode lets you use the full usable range of the battery. Also, EV mode lets you drive at higher speeds on electricity only.
In HV mode, the gas engine will kick in for power request more than ~15hp. PHV EV mode raises that to ~50hp. The EV speed limit was also raised from 25mph to 62mph. We are still working on the gauges in Torque app so, the horsepower values could be confirmed.
Also, when the engine fires up while in EV mode, excess electricity will increase the range. 3 times that happened to me this morning when the defroster kicked in. Each time, the EV range increased about 1/2 mile. It's a fascinating benefit of the power-split system often overlooked. .
