A portable GPS system consists of a unit that is not limited to in car usage. Non-portable devices are usually older models that require cable links, but the same inconvenience is found with combinations of PDAs or Palms and GPS devices that have to be car powered in order to save battery life. A portable GPS system is a unit designed for outside usage either mounted on the bike or motorcycle or carried around when hiking, mountain climbing or jogging. Even if the functionality and the features are similar, there are lots of differences between car GPS units and portable GPS systems.