Push-button ignition systems use a radio transmitter in a key fob to send a code to a computer in a vehicle, so the driver leaves the fob in a pocket or purse and pushes a button on the dashboard to engage the starter. If the code matches, the computer unlocks several systems in the vehicle, including the starter button. On most vehicles, the driver pushes the same button to shut off the engine.
Push-button ignition systems first become available in the 1990s, but they are becoming increasingly popular in vehicles, as of 2015. Both foreign and domestic manufacturers offer them as standard equipment on their cars, and post-market systems are available for cars without the manufacturer-installed unit.
While the systems offer convenience for drivers who no longer fumble with keys to start the car, they also lead to some safety concerns. Drivers are not placing automatic transmissions in park since the system does not require removal of a key. With hybrid vehicles, they can inadvertently leave the vehicle running, and it eventually switches to the internal combustion engine, with the potential for carbon monoxide poisoning.
The National Highway Safety Traffic Administration has proposed an audible alarm that reminds drivers to turn off their vehicles. A class action suit in California has called for automatic shutoff systems. However, neither system is currently a requirement.