The type of car security system you choose will likely impact the discount. Modern cars usually have passive alarm systems, so the passive alarm discount is small. Some auto insurers don't offer any discounts for these systems since they're so common. Luckily, there are other types of anti-theft discounts available.
One of the most significant cost-cutting car insurance deals available is the Remote Shutdown or Engine Disabling System Discount. Investing in this type of technology reduces the risks of theft to near zero. Other discounts to check for include tracking and recovery systems.