The title refers to Billy’s red Pontiac Firebird, which serves as the setting for many shared memories.
The lyrics emphasize that "everything changes," documenting the transition from building "homemade bombs" in the basement to moving away and starting families. Owl City - Firebird
The song serves as a nostalgic exploration of sibling bonds and the inevitable passage of time. While Adam Young is an only child, he wrote the track to capture the "special bond" he observed between Abbey and Billy. The title refers to Billy’s red Pontiac Firebird,