Car horns Car horns are a vital means of communication between you, other drivers, and pedestrians. To ensure your car is road legal, you need to make sure your car horn is working. If it fails, you must replace it. Car alarms Most cars come with basic car alarms, although third-party car alarms will offer you the best security and peace of mind. In fact, the higher the quality of your car alarm, the greater your chance of reducing your insurance premiums. To find the right car horn or car alarm for your vehicle, browse our range below.