The Vehicular Surveillance and Sensing System (VS3) is a 3G-based mobile device for car security applications. On the car side, it consists of a CS2 sensor, a camera module, a 3G module, and a microprocessor. On the user side, only a 3G mobile phone is needed. VS 3 provides the following features: (i) it can be triggered by events detected on car, (ii) events can be abnormal air quality or potential burglary, and (iii) it supports text or multimedia interaction with users. Application scenarios include detecting an abnormal CO2 level or potential car burglary, which triggers VS3 to transmit SMS, MMS, or interactive video call to the vehicle owner, who can then monitor the car situation in return. VS3 thus demonstrates a new car security and burglarproof prototype.