cooperative delivery vehicle; liaison vehicle
Specialized term used mainly in library and institutional contexts for a vehicle that transports materials between branches or cooperating organizations.
図書館の協力車が、週に一度、各分館を巡回している。
The library's liaison vehicle makes rounds to each branch once a week.
Compound of 協力 (cooperation) and 車 (vehicle). The exact origin is uncertain, but the term likely arose in library or institutional settings to describe a shared delivery service.