Keyless ignition systems have become a common feature as car buyers look for seamless connections between home, car, and the outside world. Also known as keyless start, push-button start, intelligent key, smart key, or digital key, these systems allow drivers to start their vehicles without handling a traditional key. Initially limited to luxury cars in the late 1990s, keyless ignition is now widely available. Between 2008 and 2018, it became a standard feature in 62% of cars sold in the United States, and that number is nearing 100% today.

The Mercedes-Benz S-Class was the first mass-produced vehicle with keyless ignition, followed by models from Acura, Cadillac, Lexus, and Rolls-Royce. Now, most automakers offer keyless ignition as a standard or optional feature. Brands like Hyundai, Lexus, and Tesla have even more sophisticated systems that work through credit-card-sized keys or smartphone apps.

Keyless ignition systems come with a key fob that transmits a low-frequency signal to the car’s computer, which validates the signal and allows the driver to start the engine by pushing a button. The system also includes keyless entry, letting the driver unlock the car without pressing a button on the fob. Newer versions use Bluetooth or near-field communication (NFC) through smartphone apps to perform the same functions and can even adjust settings like seat position and climate control. Although keyless ignition is considered more of a convenience than a necessity, it is a significant quality-of-life upgrade, especially for drivers with limited hand mobility or those frequently carrying multiple items.

Keyless ignition systems include safety measures to prevent accidental starts. The car’s computer ensures the vehicle is in park and the driver’s foot is on the brake before starting the engine. The fob must be inside the car, and some systems require an additional action, such as flicking a switch. The systems also deter theft, as the car’s computer only recognizes its own fob, making it harder for thieves to break in and start the engine. There’s no key to copy and no mechanical steering lock to force open. Some systems prevent locking the doors if the fob is inside or sound an audible alert. If the fob’s battery dies, manufacturers offer remote unlocking through their app or emergency roadside assistance. Some fobs even have a hidden key to manually unlock and start the car.

Despite their benefits, keyless ignition systems have introduced unexpected risks. With today’s quiet engines, it’s easy to forget to turn off the car, leading to carbon monoxide poisoning in enclosed spaces. Since 2006, over two dozen people have died from this, and many more have been injured. Drivers have also accidentally exited their vehicles while still in gear, causing cars to roll forward. Keyless systems are also more susceptible to hacking, as thieves can intercept the fob’s signal to gain access. While this type of theft is complex, it remains a concern as it can expose vehicles and personal data.

Automakers have responded by implementing safety measures such as alerts when the fob is removed with the engine running, automatic shifting into park if the door opens, and automatic engine shutoff after a set period of idling. The National Highway Traffic Safety Administration (NHTSA) is working on regulations that will require automatic engine shutoff for keyless systems, although the timeline is still being determined. In the meantime, automakers are voluntarily developing measures to address these issues.

To stay safe, the NHTSA advises drivers to read their vehicle’s manual and develop habits such as ensuring the car is in park and the engine is off before exiting. When shopping for a new car, it’s wise to consider models equipped with safety features like alerts and automatic shutoff systems. Although new regulations might not take effect for a few more years, choosing a vehicle with these safeguards can help protect against potential dangers associated with keyless ignition systems.