For some, car is just a thing of getting from one place to another while for some it is a display of personality and they want it to be as good and customized as they can afford it to be. Stereo systems, sub woofers, amplifiers and speakers are the first few things one gets installed.
GPS navigation systems are also becoming popular and are inbuilt in new cars. For safety purposes, alarms are also available which turn on when any one tries to open the car. The installation of these should be done by professionals for its proper working.