Toyota PRIUS Manual page 49

 When in HV mode
The vehicle can be used in the same way as a standard hybrid
vehicle.
In HV mode, controls are primarily carried out as follows in
accordance with the driving conditions.
 The gasoline engine stops when the vehicle is stopped.
 During start off, the electric motor (traction motor) drives the
vehicle.
 During normal driving, the gasoline engine and electric motor
(traction motor) are controlled effectively, and the vehicle is
driven with optimum fuel efficiency. Also, when necessary, the
electric motor (traction motor) operates as an electrical gener-
ator to charge the hybrid battery (traction battery).
 When the accelerator pedal is depressed heavily, drive force
from both the gasoline engine and the electric motor (traction
motor) is used to accelerate.
When braking (regenerative braking)

The electric motor (traction motor) charges the hybrid battery
(traction battery).
The EV driving range can be extended by actively using this
regenerative braking to store electricity in the hybrid battery
(traction battery).
The regenerative braking system can be used effectively to
reduce the fuel consumption also when in HV mode.
PRIUS PHV_OM_OM47831E_(EE)
1-1. Plug-in hybrid system
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