Abstract: An apparatus and method for tracking a vehicle is provided. The vehicle tracking system may include an inertial measurement unit for providing inertial vehicle state characteristics of the vehicle. The inertial measurement unit may include at least one gyro and at least one accelerometer. The vehicle tracking system additionally includes an inertial converter for generating vehicle state information from the inertial vehicle state characteristics. Clinometers are utilized within the vehicle tracking system to initialize the gyros and may additionally provide acceleration information. The vehicle tracking system may additionally include one or more redundant sensors for providing redundant state information. The redundant sensors can include an odometer/tachometer, Global Positioning System receiver, tag receiver, and a map matching system. A Kalman filter may be utilized to reduce error within the vehicle tracking system and improve the accuracy thereof.