<P> A smart key is an electronic access and authorization system that is available either as standard equipment or as an option in several car models . It was first developed by Siemens in 1995 and introduced by Mercedes - Benz under the name "Key-less Go" in 1998 on the W220 S - Class, after the design patent was filed by Daimler - Benz on May 17, 1997 . </P> <P> 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 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 . </P>

When did the first push to start car come out