Meaning: The person operating the vehicle employed a system that uses satellites to determine a location in order to find their way through a city that is not known or well-known to them.
Choice of Words: The word "driver" refers to a person who operates a vehicle. "Used" means to employ something for a purpose. "GPS" is a system that uses satellites to determine a location. "Navigate" means to find one's way through a place. "Unfamiliar city" is a city that is not known or well-known to someone.