Nowadays, the demand for accurate and reliable positioning systems is constantly increasing in several applications such as safety of life or liability critical. The global positioning system (GPS) is a world wile known and accepted navigation system used in almost any application requiring tracking. However, the quality of the localization task for ground vehicles is subjected to degrade in outdoor conditions. A severe degradation is for instance observed in urban areas, when the vehicle is subjected to multipath or masking effects interfering with the satellite lines of sight. Using usual pseudo ranges and additional measurement sources is an interesting way of improving the localization performance. This paper studies different fusion approaches based on differential odometry provided by wheel speed sensors (WSS) and inertial sensors such as accelerometers and gyroscopes. Different tracking strategies based on extended and unscented Kalman filters will be investigated and compared for these fusion approaches.