Smart key

A smart key is an electronic access and authorization of system that which is available as an option or standard in several cars. It was first developed by Siemens in t 1995 and introduced by Mercedes-Benz under the name "Key-less Go" in 1998 on the W220 S-Class following its design patent filed by Daimler-Benz on May 17, 1997.

How it works

The smart key allows the driver to keep the key fob pocketed when unlocking, locking and starting the vehicle. The key is identified via one of several antennas in the car's bodywork and a radio pulse generator in the key housing. Depending on the system, the vehicle is automatically unlocked when a button or sensor on the door handle or trunk release is pressed. Vehicles with a smart key system fitted have a mechanical backup, usually in the form of a spare key blade supplied with the vehicle. Some manufacturers hide the backup lock behind a cover for styling.

Vehicles with a smart key system can disengage the immobiliser and activate the ignition without inserting a key in the ignition, provided the driver has the key inside the car. On most vehicles, this is done by pressing a starter button or twisting an ignition switch.