From keys with key bits to smart keys and drive authorisation systems. The history of the ignition key makes a long journey. Nowadays keys feature computer units and communicate with the vehicle.

The Ignition key
User-friendly: So convenient around 100 years ago – vehicles were equipped with an ignition starter switch. Simply insert the ignition key, quickly turn it and the starter motor turns over the combustion engine. A very pleasant system, making it possible to just set off. Up to this point, the electric starter, in many cases still optional equipment, had to be activated using a separate switch. The key simultaneously acted as an access authorisation to use the motor vehicle.

Autonomy: The ignition key was quickly established as the standard. It became a beacon of modern ways and individual mobility. Keeping it on the key ring made a clear statement: owners had access to a car, steering it to their desired destination without having to accommodate the restrictions of other forms of mobility. Later in the motor vehicle’s development history, the steering was literally associated with turning the key as it not only started the engine, but simultaneously also unlocked the engaged steering wheel lock.

Making things simpler: In fact, the ignition key initially only operated the ignition lock, serving as a mechanical access authorisation. There were separate keys for the door locks. A universally suitable combination key only prevailed after the Second World War.

One impulse, all doors: The ignition key became a signal transmitter for the very first time with the introduction of central locking systems, starting in the 1960s. Turning it in the lock sent an impulse to final control elements in doors and tailgate to lock and unlock. The first Mercedes-Benz to offer a central locking system was the 300 SE with a long wheelbase (W 112).

At the push of a button: Over the years its functionality was continuously enhanced. Car keys became remote controls for doors in the 1990s. Doors unlocked and locked at the push of a button. Initially a conventional key with a key bit remained part of the package. It was simply folded out and inserted into the ignition lock.

No more key bit: The next step was to do away with the key bit. The small plastic housing resembled the shape of a key and featured an electronic system that communicated with the vehicle: the vehicle accepted the command to turn over the engine once the correct “key” had been inserted into the “ignition lock” – the command was still given by turning the key with a flick of the wrist. A slim key with a key bit was actually still included to open the driver’s door in an emergency in case the central locking system failed.

Evolution: Many cars still employed keys with a metal key bit. However, even then the plastic part of the key still accommodated electronics in most cases – to deactivate the immobiliser and provide a remote control. Depending on the equipment scope, other vehicles allowed users to leave the electronic unit in their pocket or handbag. The vehicle locked and unlocked automatically. Mercedes-Benz introduced KEYLESS-GO in 1999 in the Mercedes-Benz S-Class. And in many cases all it takes nowadays is to softly press the Start/Stop button on the dashboard to start or switch off the drive system. As a result, it is no longer necessary to turn the ignition key, the last remnant of starting the engine using the hand crank, an exhausting process dating back to the early age of the motor vehicle.

Digital: Nowadays we have compact smart keys to exchange driver profiles with the vehicle. Or smartphones feature a virtual key and act as high-tech substitutes. Sensors within the car identify the authorisation and grant access to the vehicle.

Source: Mercedes-Benz Classic