Mercedes Benz was the first to introduce the proximity system back in 1998. These remotes communicates with the receiver installed in your vehicle through radio waves to lock or unlock the doors and starts the engine once the user that carries the fob is within the acceptable range.
Vehicles with a smart key system can start the engine without inserting a key in the ignition, once the user is in the vehicle with the proximity remote. On most vehicles, this is done by pressing a starter button or twisting an ignition switch. There are also vehicles which have an ignition slot for the proximity key.
Proximity keys have an emergency key blade within the remote that may be used to open, close, and start your car. This helps in cases that the battery of the proximity remote runs out. Some vehicle can be started by using a transponder chip inside the Smart key that does not need batteries to work.
The most common feature of a smart key remote, is to enable push-button ignition this fires up the ignition of your vehicle by simply pressing a button on the dash without inserting an actual key to the ignition And another feature of the smart key remote is to activate heat or AC when the vehicle is cold or hot, and window defrosters under certain weather conditions.