First of all, it is design of the device. Car gps navigators are, most often, a candy bar in the style of a small TV that is placed on the bracket on the dashboard or hung on the sun visor. Power is from the cigarette lighter or on its own battery. Also it is worth to mention the simplicity of its interface, specially “sharpened” under the control of the navigator while driving. Car GPS have a powerful processor that lets quickly and without delay the movement of the car to “redraw” and “move” card on the display.
One of the characteristic features is the car GPS support voice guidance and automatic rerouting with describing of options and road infrastructure.
Navigator, according to the manufacturer, determines the location with an accuracy of 3-5 meters. However, a lot of things depend on the number of satellites that the device can “see” and also on the electronic cards.