An electronic key a vehicle is disclosed. The electronic key includes an inertial sensor, a microcontroller coupled to the inertial sensor and a transmitter/receiver coupled to the microcontroller. The microcontroller is configured to perform an operation, the operation includes detecting a motion, turning a radio of the transmitter/receiver on, determining that a distance to the vehicle is less than a preselected distance, determining an activity using a sensor fusion process, determining that the distance to the vehicle is decreasing and performing a preselected operation on the vehicle.