Abstract: A vehicle security system for protecting a vehicle from carjacking and from theft while the vehicle is unattended. The portion of the security system which protects the vehicle from theft while the vehicle is unattended is selectively initiated by pressing a command button on a remote control transmitter. In response thereto, a first disablement sequence is initiated which includes disabling the vehicle. The portion of the security system which protects the vehicle from carjacking is automatically initiated by the starting of the engine. A second disablement sequence is initiated upon either the sensing of a door opening while the engine is running or upon receipt of a signal transmitted by the remote control transmitter. The second disablement sequence provides a warning to persons inside and outside the vehicle prior to engine disablement and the actuation of a plurality of sirens.