Automatic Locking Doors premiered on the 2018 Outback and Legacy. Owner's of these units can reference Chapter 2: Keys and doors/Door locks in the owner's manual for more information. Online versions of the owner's manual is available on the Vehicle Resource page of Subaru.com. Below is an excerpt from the owner's manual, page 2-8, about the feature.
"All doors are automatically locked when the vehicle speed reaches more than 12 mph (20 km/h). When the driver’s door is opened, all doors, including the trunk or rear gate, are automatically unlocked."
"All doors are automatically locked when the vehicle speed reaches more than 12 mph (20 km/h). When the driver’s door is opened, all doors, including the trunk or rear gate, are automatically unlocked."