Gone are the days when car alarms were simple noise-making devices, designed to go off when someone disturbed a vehicle (as when trying to steal it). Because of the growing ineffectiveness of purely "loud sound" alarms, manufacturers are graduating to more intelligent systems.

Several studies have shown that people, especially in congested cities, have stopped responding to car alarms. This is because most car alarms are set off not accidentally by passersby or by trucks and other vehicles that cause the ground to vibrate. This indifference radically diminishes the theft prevention capabilities of car alarms.

Car alarms are now shifting from just plain sound-making devices into smarter, more interactive forms. Manufacturers are continuously developing "immobilizers" that shut down the car's engine when someone forces the doors open and starts the car without using authorized access methods (such as car keys or pass codes). Other forms of immobilizers are controlled using the same technology used in text messaging or SMS - once the owner finds out that his car is missing, he simply presses a button or calls a relay station to activate the car's immobilizer. The stolen car then stops wherever it is.

Some car manufacturers now add in vehicle tracking systems. These nifty gadgets enable the police to trace stolen cars. Note that both of these gadgets are still quite expensive. Manufacturers have yet to find ways to mass produce and them at more affordable prices.

While hybrid immobilizers and tracking systems protect against car napping, they still do not protect against vandalism or theft. In these cases, it's still a good old fashion car alarm that will do the trick. This is probably why many car owners still can't let go of the trusty device.