Units of measurement (Score 1)

The main issue around incar navigation systems is that GPS was design for battlefield (open terrain) and not for guiding cars down the freeway. When used in cities GPS has problems due to multiple signal paths which cause errors in location calculation additionally to get a good locational fix any GPS ground device needs to see 3-4 satellites which is difficult due to high rise buildings. All in all GPS is only accurate to about 200-300 meters in a city, which makes navigation very difficult