I think the more popular a car alarm system is more the chances of it getting broken into. Because car thieves come prepared for the most common deterrents they will encounter. What we need is more proprietary systems that throw off potential thieves, delay and confuse them. Any defense mechanism that takes them a long time to crack will put off thieves.
I have an idea for a car alarm system. It uses old school infra red tech. This is only to counter thieves who would try to steal the car from your garage.
The idea is to have a infrared transmitter in the car and another infrared receiver in the garage on the wall right in front of the car. When the alarm is activated the receiver and transmitter are in line of sight and hence the alarm does not go off. But if someone interrupts the beam (if they try to move the car) the alarm goes off. Again this is the basic idea and it can be worked on and improved to add more features.