What you need to know about keyless ignition systems

In an era in which convenience is king and car buyers seek more seamless connections linking home, car and the outside world, keyless ignition has become a nearly ubiquitous automotive feature. Also called keyless start, push-button start, intelligent key, smart key or digital key, this feature allows you to fire up your car's engine without fumbling for a key in your pocket or purse.

Keyless ignition was initially only available on luxury cars starting in the late 1990s, but it has become increasingly common. From 2008 to 2018, it became a standard feature on 62% of cars sold in the United States, and today that number is closing in on 100%.

The Mercedes-Benz S-Class is generally recognized as the first mass-produced car with keyless ignition, followed by models from Acura, Cadillac, Lexus and Rolls-Royce. Now nearly every automaker offers keyless ignition as a standard or optional feature, and brands like Hyundai, Lexus and Tesla include sophisticated systems that work through credit-card-like keys and smartphone apps, Edmunds reports.

How keyless ignition works

Keyless ignition systems come with a fob that you can keep tucked away in your pocket, purse, backpack, briefcase, or really anywhere near the receiver inside the vehicle. The fob transmits a unique low-frequency signal to the car's computer system, which then validates the signal and allows you to push a button on the dash or console to start the engine. Shutting off the engine is just as easy: Simply press the start/stop button. Most modern systems also include keyless entry, allowing you to enter the car without inserting a key or hitting a button on the fob.

The newest systems take entry and ignition a step further. Smartphone apps use Bluetooth and near-field communication protocols to perform the same function as a low-frequency radio signal. This tech evolution offers even more convenience, as the app can also communicate to the car the driver's preferences for seat, climate and even radio settings.

Even though keyless ignition and entry are now widely available, they're still more of a convenience than a necessity like power windows and door locks. But for many car shoppers, they offer a unique selling point. Keyless systems can be a major quality-of-life upgrade for a variety of people, from frazzled parents with constantly full hands to workers and students juggling bags, tools and books to drivers with arthritis or other disabilities that limit their ability to grip and turn a key.

Security measures

Keyless ignition systems include safeguards to ensure that your car doesn't spring to life when it shouldn't. Pre-start safety checks by the car's computer ensure that the vehicle is in park and that your foot is on the brake before allowing the engine to start. Some designs require you to flick or rotate a switch before pressing the start button. And in most cases, the key fob must be inside the car in order to start the engine.

Among other advantages, these systems are designed to help deter break-ins and vehicle theft. Since the car's computer will only recognize a signal from its own fob, thieves have a harder time getting in and starting the engine. There's no metal key that can be copied and no mechanical steering-column lock that can be forced or otherwise defeated.

Keyless ignition also makes it harder to lock your keys in the car or the trunk. For one thing, the fob can always remain in your pocket if you choose. But some systems are smart enough to prevent locking the doors if, for some reason, you leave the fob inside the vehicle or in the cargo area. Others send an audible alert if you attempt to shut a door or trunk lid with the fob inside.

And if the fob's battery goes dead while you're away from home, most systems have you covered, though the approach varies among carmakers. A common solution is remote unlocking via the automaker's over-the-air emergency service. When you call or use the company's mobile app, a representative can send a signal to unlock your car doors and activate the starting system. Other automakers offer emergency roadside assistance that will send a technician to bail you out. And some systems even have a hidden key that pops out of the fob to unlock the door. The key can then be inserted into an emergency port to start the car.

The problems with keyless ignition systems

Unfortunately, there have been a number of unexpected, and sometimes tragic, dangers associated with keyless ignition. Although automakers and the National Highway Traffic Safety Administration are taking measures to address these issues, you should be aware of some potential downsides.

Keyless ignition, combined with today's exceptionally quiet engines, can make it easy to forget to actually stop the engine when leaving your car. Since 2006, more than two dozen people have died from carbon monoxide poisoning after leaving a car running in an enclosed garage that was attached to a house, and many others have suffered illness and injury.

Many people have also been injured or suffered property damage as a result of getting out of a vehicle without first putting the transmission in park. With a softly running engine and no key to disengage, drivers can inadvertently step out of the car while it's in gear, allowing it to lurch forward, dragging them along with it and possibly running into another vehicle or a wall or other obstacle.

Keyless ignitions are more vulnerable to hacking than those with conventional starting systems. Research teams have demonstrated that with the right equipment, it's possible to "capture" the radio signal from a keyless fob and use that signal to open and even start the car. This kind of theft is a lot more complicated than smashing a window, but determined and tech-savvy criminals have already broken into cars this way. Additionally, the increased commingling of car communication and personal smartphone data opens a vulnerability to data theft. Even though these require fairly sophisticated electronic tools and savvy hackers, it remains a risk.

What's being done?

Automakers have responded to the problems associated with keyless ignitions by implementing a variety of solutions. Some models sound an alert, either by honking the horn or triggering an alarm, if the ignition fob is removed from the vehicle with the motor idling. Some vehicles are equipped with devices that automatically shift their transmissions into park when a door opens. And a few systems will automatically shut off the engine if it's left idling for more than a specified amount of time.

As part of the Infrastructure Investment and Jobs Act, the NHTSA has introduced regulations that will compel automakers to include an automatic engine shutoff feature on keyless systems. The length of time allowable before the engine shuts off is still to be determined, but it should be long enough that a vehicle won't stall out while sitting in traffic but not too long as to pose a risk of carbon monoxide poisoning. In the meantime, automakers say they are in the process of voluntarily developing ways to protect the public from the potential dangers of keyless entry and keyless start.

How to protect yourself

First and foremost, the NHTSA suggests reading your owner's manual carefully to be sure you know how to operate your vehicle's keyless ignition system properly. The agency also says it's essential to develop good driver habits, such as making sure your car is in park and the engine is shut off before departing from the vehicle. The NHTSA also suggests watching its video on basic safety tips for living with keyless ignitions.

It's also smart to research the systems while you're shopping for a new vehicle. Many of the latest models are equipped with alarms and other safety devices that prevent drivers from leaving a vehicle running or in gear. And while regulations regarding automatic engine shutoff are pending, these likely won't take effect for another model year or two. If the cars you're considering have keyless ignition systems, make sure your next car has these kinds of safeguards too.

Edmunds correspondent Dan Frio contributed to this article.