A remote car starter lets you use a control button on your key fob to start the engine while you’re not in the driver’s seat. In fact, you don’t even need to be outside. The idea is to leave the heat on (in the winter) or the air conditioner on (in the summer) when you park. Then when you start up remotely, the interior temperature has plenty of time to adjust to your liking before you go out, get in, and start to drive.

The nice thing about these devices is that they let you thaw the ice off your windshield if you’ve parked outside. And if you’ve parked in the sun on a hundred-degree day, you won’t burn your hands when you grip the steering wheel, or other parts of your anatomy when you sit down on the upholstery.

There are plenty of safety features. A good sytem will leave your vehicle locked when you hit the remote button, so nobody will steal it. Before you can actually drive, you have to turn the key in the ignition. And you can turn off the engine with the key fob, as well as turn it on.

Basic features found on most systems include remote engine starting, programmable starting to set how long the vehicle will run before automatically shutting off, a visual indicator that you’ve started the car like flashing the parking lights, power door locks, and power trunk lid operation.

Advanced features in addition to remote car start usually involve a combination car alarm remote with full a full vehicle security system. You’ll find items like an outside air temp sensor that will automatically start the engine at a certain temperature, an LCD display panel, long-distance transmission features so you can start your vehicle through cement walls and from up to one mile away, and a rolling code feature so thieves can’t copy the starter signal and steal your vehicle with it.

The price of a basic car remote can be as low as $40. High end car alarm remotes can cost up to $400. Don’t forget to add on the cost of installation, unless you plan to install the system yourself. Some vehicle models will require an adapter that bypasses your factory installed ignition lockout or car alarm system, and these can add another $50 to $100 to the price tag.

If you drive a manual transmission, be sure the remote starter system you buy is compatible with a stick shift. Also, some systems only work with fuel injected engines. Again, check the system’s specs for compatibility.

This type of system is triggered by either a key fob attached to your keychain, or by a device built into the plastic grip on the key itself. One button unlocks your car; the other one locks it. A third button opens the tailgate or trunk, and a fourth button, usually red, activates and deactivates a pulsing series of horn blasts to alter passersby if your safety is threatened. If your car is equipped with a car alarm, the fob will also have buttons for activating and deactivating the vehicle security system. Many keyless entry remotes will also close your sunroof and roll up the windows you left open when you send the signal to lock the doors.

Your keyless entry remote fob is a miniature radio transmitter that acts as an electronic key to your vehicle’s doors. The signal is much like the ones used in radio-controlled toys. The fob also contains a circuit board, an antenna, and a battery. Pushing one of the buttons on the fob activates the transmitter, which sends a signal to the receiving unit inside your car. The receiver is tuned to the same frequency as the transmitter. It looks for a signal that matches the one it’s been programmed to receive. If it gets one, it unlocks your doors.

An automotive keyless entry system performs all the functions of a normal car key, but without touching the vehicle. You can lock and unlock your power door locks from up to 50 feet away (depending on how fresh the battery is), and even from indoors. Just like a normal key, locking your keyless remote fob inside your vehicle is a problem if you don’t have a spare.

So much for how it works. But is it secure? To understand the answer to this question, you need to know the history behind this type of system.

The precursor of keyless entry locks was the good old automatic garage door opener that first came into wide use in the 1950s. The transmitters in these units were so simple that they all sent out the same signal. It didn’t take long for thieves to figure out that they could open all the garage doors on one street with just one transmitter.

The 1970s saw the advent of DIP switches in garage door openers. These were an eight-switch transmitter that you programmed with a keypad and matched the code up with the receiver inside your opener. This was improvement over the original design, but eight switches only had 256 possible combinations—enough to discourage opportunistic theft, but no match for professional thieves, and not secure enough to use in automotive applications.

Modern keyless remotes began in the 1990s with the introduction of a small computer chip in the transmitter unit that can generate literally billions of possible codes. At this point, automobile keyless entry became standard equipment on all but the cheapest cars. Car thieves responded by using laptop computers with wireless cards to pick up the signal from a car owner’s key fob. They would store the signal and track the owner to where he left his vehicle, then stole it.

The vehicle security industry’s response was the 40-bit rolling code, also called a hopping code. This type of keyless entry lock generates a new code sequence each time you use your key fob to open or close your car door. The receiver chip inside your car is synchronized with the transmitter on the key fob to accept the new code as the fob generates it. The thief who picks up the code sequence you use to open your car will find that it doesn’t it work if he follows you to a parking lot and tries to use it after you’ve left your vehicle.

One problem with rolling codes is that if you get out of range of your car and then press the button on your key fob, the keyless entry chip in your car won’t know what the new hopping code sequence is. In that case, the receiver chip is programmed to predict the next 256 hopping codes that your key fob will generate and accept any of them. So unless you accidentally push the button 257 times, your keyless remote will still work when you push the button.

The same technology found on these systems is also used on radiofrequency ignition devices (RFIDs). This is a car theft prevention technology which locks out your ignition system until you send it a signal to unlock by either pressing a button on the key fob, or inserting your key in the ignition.

When you go shopping for a vehicle alarm, you’ll find two major types of car alarm triggering mechanisms: Active car alarms make you press your car alarm button to activate and deactivate your vehicle security system. Passive alarms are “smart alarms” that automatically arm themselves after you turn off the ignition and close all of your doors. A quality auto security system will let you set it to either passive or active mode, while a cheap car alarm will probably only have an active mode.

Put in a call to your insurance carrier after you buy your vehicle alarm and find out if they will offer you a discount on your policy for investing in some car security. Passive auto alarm systems are especially good candidates for insurance discounts.

If you’re having an aftermarket stereo system installed, have your car alarm system put in at the same time. You don’t want a thief to steal your stereo while you’re waiting to have a remote alarm put in.

Cheap car alarms are just that—cheap. Stick with brand names, because they don’t cost that much more, and your protection is worth it. The base price on a good quality auto alarm is around $100. When you get into the $200 range, you should be getting some major features in the unit. To have the unit installed will cost you a minimum of $100 and possibly more, depending on how complex the extras are to install. The physical appearance of the finished installation varies from installer to installer. Installation on a show vehicle will definitely cost you more money.

There are many types of car alarm features available, with more being added to the list all the time. Look for these extras when shopping for a vehicle security system.

Anti-code grabbing protection changes the alarm’s code every time you arm or disarm it. This should protect you from equipment that can grab your code from anywhere within signal range and save it for the thief who wants to come back and use it later. A microwave detector can sense when objects or people enter the protection zone but before they touch your vehicle. Carjack protection protects you from having your car taken by force by turning off the engine and setting off the siren. Tracking devices like LoJack are built in transmitters that law enforcement personnel can use to track your vehicle after it’s stolen.

Noisemaking devices have gotten louder and more effective with the advent of sophisticated car alarms. The basic siren is the noisemaker that everyone hears when the alarm triggers. They are usually set up in the engine compartment. A pain generator is a louder siren, usually an air horn, which goes in the passenger compartment and is intended to hurt the thief’s ears. Air horns can also be placed under the hood for extra noise.

Flashing lights are also part of a car alarm’s attention getting strategy. Basic systems will flash the headlights and parking lights on and off rapidly, along with flicking them when you arm or disarm the system so you can confirm that the alarm picked up the signal from your key fob. Strobe lights are additional features on high-end units and emit intense, pulsating light to attract attention. A few systems even fill the interior of the car with harmless smoke.

There are many convenience features on a good car alarm system too. Your alarm key fob should allow you lock and unlock your car doors without activating the alarm, along with a trunk release button to help you out when your hands aren’t free to open the trunk manually. Key-in features activate when you place your key in the ignition, such as automatic dome light activation. An ignition and/or starter disabling switch prevents the car from being started until you release it by inserting a specially coded key in your ignition.

Safety features on modern car alarm systems include an emergency disarm switch, or a valet switch. This is a hidden switch that will temporarily disable the alarm in case of malfunction or loss of the sending unit. You should get an OEM disarm feature on your aftermarket car alarm unit if your car has a factory installed alarm, because the two units often end up in conflict with each other.

You can get extra theft protection with features like a Window Roll-up Module, which will roll up the power windows on your car when you arm the alarm. An active re-arm feature will automatically set the alarm to “on” after a preset amount of time passes unless you actually open a car door. This keeps you from accidentally disarming your alarm after you leave your vehicle. Finally, every alarm system should have the flashing red LED light on the dashboard to provide a visual deterrent to thieves who might be thinking of stealing your car or something in it.

Other high-end types of car alarm features include car alarm pagers, which will send a signal to a paging unit that you carry with you when someone triggers the alarm sensors while you’re away from your car. Remote starter units let you start your car from inside your house with a sending unit on the key fob, to warm it up in the winter or cool it down in the summer.
Here’s a glossary of car alarm terms to help you choose the best alarm for your needs.
Channels: how many outputs on an alarm has you can control with the transmitter.
Disarm: switching the alarm to an inactive state.
Pin Switches: a triggering device placed in your car’s doors, hood or trunk. Pin switches close or open an electrical circuit when they’re compressed or released, sending an electric current to the alarm brain.
Zone: An area around or in the vehicle that is guarded with some kind of sensor.
Arm: switching the alarm to an active state.
Transmitter: also known as a key fob, this is a small device you carry on your keychain and use to arm/disarm and control the alarm.
Relay: a switch that takes an incoming low current and closes a mechanical switch that steps the low current up to a much higher current
Brain: the main switching board of the alarm that controls all of the sensors and connected
Trigger: A signal to the alarm brain from the pin switches and other sensing devices, activating a response within the brain.

Alarms might not stop a thief in his tracks, but they attract plenty of attention, which crooks hate. Here’s some other miscellaneous advice to help you keep your car or the valuables inside it from being stolen.

Don’t use stickers and decals that might make a bystander think you have a lot of money to spend on flashy gear, or might have that gear stored in your car. Looking hip isn’t worth putting out an invitation for thieves to steal your stuff.

Driving around in neighborhoods with your windows down and your stereo blasting is asking to have your car or stereo stolen.

When you park your car, put it under good street lighting and in full view of pedestrian and car traffic.

Don’t customize the exterior of your car with aftermarket add-ons that suggest more goodies inside. Keep the flash on the inside where no one can see it and keep the exterior all stock.