The rolling unit is called an AGV - Autonomous Guided Vehicle. It is a self contained car with power, wheels, computers and such, and follows a guide wire (or puck) in the floor. The floor is level.
I can`t find the car figure at the mo; I`m sure a resident bellhop will help. Yes, they can store cars if needed and swap faulty ones out. Try a thread search for diagrams of the attraction![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
I can`t find the car figure at the mo; I`m sure a resident bellhop will help. Yes, they can store cars if needed and swap faulty ones out. Try a thread search for diagrams of the attraction