Driving is a social activity. Previously, the "social car" topic, which attempts to enhancing communication between drivers, received much attention by the Auto UI community. However, due to the limitation of the infrastructure, accuracy of the GPS, the popularization of the V2V technology etc., it is difficult to realise these social applications on the road at present. We proposed a prototype "HUD-AR", which utilizes camera of smart phone and computer vision technology to recognized other road users and transfer social information. "HUD-AR" is an affordable solution to connected drivers, and provides insights and inspiration to the industry.