TL*THE CONTACT OWNS A 2005 SUBARU IMPREZA. WHILE PARKED ON AN INCLINE WITH THE PARKING BRAKE ENGAGED, THE VEHICLE ROLLED DOWN A HILL, CRASHED THROUGH FENCES, AND STRUCK A MAILBOX. THERE WERE NO INJURIES. THE VEHICLE IS CURRENTLY AT A REPAIR SHOP AWAITING FURTHER INSPECTION TO DETERMINE WHY THE EMERGENCY BRAKE FAILED. THE POWERTRAIN WAS UNKNOWN. THE CURRENT AND FAILURE MILEAGES WERE 21,307.