Modern cars are equipped with sophisticated electronic security systems, which require the use of a specific key or fob to start the engine. These keys contain a unique code or a transponder chip that interacts with the car's immobilizer system. The immobilizer system prevents the engine from starting if it does not recognize the correct key.
An emergency key, on the other hand, is designed to unlock the doors mechanically. It does not have the necessary electronic components or the transponder chip required to communicate with the immobilizer system. Therefore, it cannot be used to bypass the immobilizer system and start the car.