The present invention relates to a connecting device (8) arranged in a motor vehicle (1) for releasably connecting a structural member (2) of the vehicle (1) to the vehicle chassis (3), said connecting device (8) comprising a bolt joint system (9). The connecting device (8) further comprises a pyrotechnical charge (23) and an igniter (23), said igniter (23) being adapted to, when receiving an ignition signal, bring said pyrotechnical charge (23) to detonate, said pyrotechnical charge (23) being located near the bolt joint system (9) such that it, upon detonation, destroys the connecting function of the bolt joint system (9), for releasing said structural member (2) from the chassis (3).