According to the most recent FBI statistics, over 750,000 vehicles are stolen every year in the United States — that’s more than one every minute. While fitting a car alarm won’t always stop a professional criminal, it can be very effective at preventing the kind of casual or opportunistic theft that happens most of the time.
Most car alarms work on very similar principles. While you might pay a little extra for some of the top brand names, mostly it’s a question of the number of features you want. More features might equal a higher price. However, there are plenty of choices, and many of them are surprisingly inexpensive. We’ve been assessing the merits of many different systems so we can help you decide which is right for your vehicle.
Our recommended products cover a range of budgets and different levels of performance. If you’d like to know more about the features available, continue reading our buying guide.
Across the US, a vehicle is stolen every 41 seconds. If you don’t have a car alarm, it’s easier for the thieves to take yours next.
Alarm activation can be passive (the system comes on automatically when you shut the car door, for example), or active (you have to press a button to activate the system). Many budget alarms don’t offer a choice and are usually active only.
The alarm is triggered usually by a shock or vibration sensor. A big criticism of older car alarms was that they would go off at the slightest touch. Good modern versions — even basic models — have a two-stage sensor. The response to initial contact is a warning chirp. The alarm goes off only if there’s subsequent contact. Better alarm systems also have a sensitivity adjustment, so you can reduce the occurrence of false alarms.
Sirens are usually 120 decibels or more — not the kind of noise that’s easily ignored! Many systems also flash the vehicle’s lights.
One-way vs. two-way systems
One-way: Low cost and mid-range car alarms are usually one-way systems. In other words, the handheld transmitter (the remote) sends a signal to the car to perform a particular function.
Two-way: More expensive models are two-way systems. The car can return information to the remote, which has a screen to display information (usually only one of the two provided remotes can do this). It might inform you if someone is tampering with your vehicle or if the engine has been started. The range varies, but on some it’s up to a mile.
Though it generally requires adding another unit to they system, some car alarms can be linked to a smartphone to provide two-way communication over virtually any distance. You might be too far away to do anything about the tampering yourself, but it would enable you to inform law enforcement if there’s an attempt to steal your vehicle.
Locks and windows
Doors: Most remotes can unlock and lock doors if your vehicle has the appropriate door actuators. Older vehicles may not have these, but they can be retrofitted.
Trunk: The ability to open the trunk may also be provided. More advanced models can close the windows for you.
Ignition: The system might also have ignition locking: the doors are locked when you start the vehicle (helping to prevent carjacking) and unlocked when you turn the ignition off.(Video) 14 NEW CAR GADGETS YOU SHOULD BUY
Some alarms can start the car for you, too. They may also have an engine kill switch, so if you suspect there’s a problem, you have another immobilizer even if the thief has bypassed a factory-fitted version.
Car alarm system features
Basic car alarm systems may have few features, but if they have auxiliary ports it’s possible to add more functionality at a later date.
Panic alarm: A panic alarm is a one-touch method of activating the alarm when you’re inside the vehicle so you can lock the doors and signal for help. The volume of the alarm may well be enough to deter an attacker.
Emergency override: This is included on some systems, allowing you to disable the alarm if you lose or damage the transmitter.
Valet mode: This is another option. It disables the system when you’re handing the car over to someone else. This is useful not only for valet parking but also when you’re at the dealership, mechanic, and so on.
Random codes: There is a potential danger of someone cloning your remote, and some systems have random rolling codes to prevent this. It’s a useful extra, but a thief with the technical skills and equipment to clone your remote could probably find a quicker and easier way to bypass your vehicle security anyway, so it isn’t seen as a major feature.
Is a car alarm worth it?
Unfortunately, there’s no guarantee that any alarm system will keep your car from being stolen. Even with the most effective immobilizers and alarms, if a thief is determined to take your vehicle, they will find a way to do it — even if it means loading it onto a flatbed truck!
What a car alarm system does provide is a cost-effective way to deter the casual criminal, the one who goes around streets and parking lots checking door handles or has a length of steel up their sleeve to jimmy your door locks.
Having a car alarm system might lower your insurance premium (talk to your broker), and it will almost certainly add to the resale value of your vehicle. Given the relatively low cost, it could make economic sense.
Car alarm system prices
Inexpensive: The cheapest car alarm systems cost between $25 and $35. They aren’t very sophisticated, but it’s very little money for the additional protection it offers your vehicle.
Mid-range: There are lots of very good one-way car alarms in the $40 to $70 range. In our opinion, this is the sweet spot. Pretty much everything you could want, from the industry’s top names, falls into this bracket.
Expensive: What pushes prices beyond the mid-range are things like two-way communication, with remotes that have LCD screens to provide additional information. Depending on the range provided, these can run anywhere from $130 to $250. If you want smartphone connectivity, it could add another $150 or more to the cost.
A car alarm is a primary deterrent, but there are other things you can do to make your vehicle less attractive to thieves.
Never leave your car unlocked.
Close the windows and sunroof when the car is unattended.
Park in a well-lit area at night.
Don’t leave items visible inside the car. Bag, pocketbook, wallet, laptop, phone — take them with you or put everything in the trunk and out of sight.
- Don’t leave your car idling unattended. On a cold morning it might be tempting to start your car in the drive to warm it up and then pop back inside for a few minutes. Thieves wander neighborhoods looking for opportunities just like that.
Car alarm systems draw very little current, so if your vehicle’s battery is in good condition, it can power your alarm 24/7 for several weeks.
Q. Are car alarms difficult to install?
A. It depends on the alarm, but the ones we’ve featured are relatively easy. Instructions aren’t always great on cheaper car alarms, but there are lots of online videos that can help you. If you’re at all unsure, your local auto electrician will be able to do it, and it shouldn’t take them long.
Q. My car already has an immobilizer. Do I need an alarm, too?
A. Most professional car thieves know how to get around a standard factory immobilizer, and recent headlines tell us they can do it in as little as ten seconds! Your factory system probably doesn’t have movement sensors or the mega-loud, attention-grabbing siren. While a determined criminal could eventually disable your alarm, too, it’s an extra layer of protection and relatively inexpensive, so it’s certainly worth considering.
Q. I’ve heard that installing an aftermarket car alarm system can void my warranty. Is that true?
A. No. The Magnuson-Moss Warranty Improvement Act of 1975 protects you from unscrupulous dealers who say only authorized parts can be added to your vehicle. However, if you damage the existing wiring or circuitry in any way, then you could be in trouble. If you’re not confident, get your car alarm professionally installed.