In my experience, you're correct. "Shotgun", "copilot" and "navigator" are all terms used interchangeably in my family. And urban dictionary has entry for 'c

In my experience, you're correct. "Shotgun", "copilot" and "navigator" are all terms used interchangeably in my family. And urban dictionary has entry for 'co-pilot' from 2005 referring to the shotgun passenger.