Infrared "SmartKey" Standard on All Mercedes-Benz Models

An infrared SmartKey is standard equipment on every Mercedes-Benz for the 2012 model year. The latest SmartKey features more distinct buttons that are easier to operate without looking at the unit.

Mercedes-Benz SmartKey Can Include KEYLESS-GO

Walk up to your locked car, simply pull the door handle, and the car unlocks. Key still in a pocket or purse, you sit down in the driver's seat, press the brake pedal, push an "Engine Start" button, and the engine burbles to life. Science fiction? No, it's a real-world option on many Mercedes-Benz models.

Low-power radio transceivers in the doors sense the presence of the SmartKey with KEYLESS-GO in the driver's pocket or purse. When a small button on the door handle is touched, the doors are locked, and they can be unlocked simply by touching any part of the door handle. Without a key of any sort in the ignition slot (the slot's still there, in case you prefer), the engine will start whenever a button on the dashboard is pushed (the SL roadster uses a button on top of the shift lever). For safety reasons, the brake pedal must also be depressed with the shift lever in Park for the engine to start with the KEYLESS-GO button.

SmartKey Ahead of the Industry

With or without KEYLESS-GO, all Mercedes-Benz vehicles come with a standard SmartKey – also ahead of its time. Gone is the conventional mechanical ignition key, in favor of a fully electronic key that's integrated into the remote locking unit.

One end of the remote unit simply fits in the "key" slot. The industry's first fully electronic ignition key employs no metal key that could be illegally copied and, as a result, makes it nearly impossible to unlock the steering column or start the engine without the owner's remote unit.

Dual-Mode Signals

For the best combination of security and convenience, SmartKey uses a dual-mode remote system – radio- and infrared-frequency signals. The unlock button can operate the driver's door only, or all doors plus the trunk and gas filler door. On most Mercedes-Benz vehicles, simply holding down the unlock button activates a useful "summer opening" feature that lowers all windows and opens the sunroof to clear hot air trapped inside a parked car. Conversely, holding down the lock button will close all windows and the sunroof. For safety reasons, however, the driver must aim the key at the driver door.

The driver operates the SmartKey in the same fashion as a conventional system. The unlock button on the remote unit unlocks the door, and the SmartKey fits the ignition and twists. As the driver turns the key, infrared data is exchanged in a split-second. If the correct code is sent back, the steering column is unlocked, the ignition circuit is switched on, and the starter operates. As a double security measure, the system changes codes each time the car is started. Also, the driver need only turn the key to the start position. The vehicle disengages the starter at the precise moment the engine fires, preventing the starter gears from potentially clashing.

Hidden inside the SmartKey unit is a small conventional key that can be detached to lock the glove box (and trunk on sedans, coupes, convertibles, and roadsters), then pocketed before handing the remote to a parking valet. Additionally, the metal key unlocks the door if the battery in the remote fails. However, since data exchange from the car works even when the SmartKey battery is dead, the car can still be started with the remote key.