Toyota PRIUS Manual page 132

1-4. Opening, closing and locking the doors
 Effective range (areas within which the electronic key is
detected)
Vehicles with entry function of driver's door
132
PRIUS PHV_OM_OM47831E_(EE)
When locking or unlocking
the door
The system can be operated
when the electronic key is
within about 0.7 m (2.3 ft.) of
driver's door handle.
When starting the hybrid
system or changing
"POWER" switch modes
The system can be operated
when the electronic key is
inside the vehicle.