This document summarizes two articles about GPS car navigation systems. The first article describes the two types of systems and how to use them, including selecting a destination and route. The second article explains how GPS systems work, including GPS satellites, location calculation, and trip planning. The document is divided clearly and includes details about using the navigation systems. Some points of confusion include lack of images and definitions of technical terms. Suggestions for improving include adding images, defining terms, and describing what to do if errors occur.