Effectiveness
Since most car alarms are triggered accidentally (frequently because of high sensitivity settings), people often ignore alarms. The New York City Police Department claims that car alarms are actually making the crime problem worse because false alarms are so common that people simply ignore them.
Because of the large number of false alarms with car alarms, many vehicle manufacturers no longer factory-fit simple noise-making alarms, instead offering silent—but effective—immobilizers. Alternatively, an aftermarket vehicle tracking system can enable the police to trace stolen vehicles. Most police tracking systems require the user to pay a recurring fee, whereas factory immobilizers are included in the purchase price of the vehicle. GPS locating systems enable the owner of the vehicle to lock and unlock, track, and disable the starter of the vehicle online.
Frequently, false alarms occur because car alarm owners use high sensitivity settings. This may be the main reason why loud bass frequency sound (loud music, other cars or motorcycles with loud exhaust systems, thunderstorms, etc.) can set off car alarms. The second possible reason is that some parts of the alarm system may be improperly installed.
Yet another class of security covers aftermarket car alarms that include 2-way paging controllers. Some 2-way systems have an LCD icon display that can pinpoint the part of the vehicle being threatened, and many alert the user with beeps or silent vibration.
Read more about this topic: Car Alarm