It may seem strange for those who are used to starting a car the traditional way, but some automakers are coming up with alternate methods to using a key. The Mercedes C class doesn't require inserting a traditional key in the ignition cylinder thanks to a technology called Keyless-Go. You use a smartkey that fits in your pocket and communicates with the security system. A wireless signal verifies that you have the smartkey, and you use a push button to start your Mercedes.
Touch the inside of the driver side door handle to unlock the door. You must have the smartkey in your pocket or within one meter of the door in order to unlock it. The security system and smartkey use a radio frequency to verify your right to open the vehicle.
Open the door and enter the Mercedes, then close the door behind you. Check that all doors are closed, as the engine won't start with something left open. Also be sure you have the smartkey in your pocket still as the engine starter won't work without it. The system also prevents you from locking the doors with the smartkey inside.
Depress the brake pedal fully and hold it there. If the car has a manual transmission, set the gear to neutral.
Press the ignition button once to start the engine. You can now release the brake pedal.
You do have an emergency key that you can remove from the smartkey device and use to start the engine the traditional way. You will need to remove the start button on the ignition cylinder to use the key.