METHOD AND SYSTEM FOR PASSIVE START OF A VEHICLE

The disclosure relates to a method performed by a within-vehicle-confirming system on-board a vehicle for establishing that a key device is within an interior of the vehicle. The system determines that there is a secure communication link between the vehicle and the key device. The system further provides a vehicle sound signal within the interior of the vehicle. Moreover, the system receives from the key device a key device signal via the secure communication link, which key device signal is derived from a sound signal detected by one or more sensors associated with the key device. The system further compares the vehicle sound signal with the key device signal, and enables a start of the vehicle when the key device signal matches the vehicle sound signal. The disclosure also relates to a within-vehicle-confirming system in accordance with the foregoing, and to a vehicle at least partly comprising such a system.