On my parents Prius there is some logic involved in weather or not the doors unlock automatically. If you open the driver's door it will unlock automatically,

On my parents Prius there is some logic involved in weather or not the doors unlock automatically. If you open the driver's door it will unlock automatically, the other doors will be locked. If you open a passenger door all doors on the car are unlocked. Either way it is always possible to unlock at least one door with out hitting a button. The car can start as long as it can see the key and will keep running even after the key has been removed.