Wireless technology has been widely used for applications of wireless Internet access. With the matured wireless transmission technology, the new demand on wireless applications is toward the concept of deploying wireless devices on transportation systems such as buses, trains and vehicles. Statistics of car accident cases show that car accidents are often caused from drivers unnoticing other approaching cars during driving. Without the assistants of automotive personal computer system (also called as Auto PC), during high-speed moving, driver always counts on himself/herself to look for all vehicles around him/her via limited vision and acoustic recognition. In case that the Auto PC is able to provide useful surrounding information, such as the directions and distances to nearby vehicles, to drivers, unnecessary collisions could be obviously avoided, especially in cases of changing lane, crossing intersection and making a turn. In this paper, we will introduce the concept of automatic distance and direction awareness system (DDAS) and describe the designed embedded DDAS integrated with three-wheel and four-wheel robot cars.