Annotation: This paper gives an overview of uncertainty analysis of inertial measurement system intended for characterizing and comparing ground vehicle driving abilities in real world condition tests. For constructing measurement function and model, sources of system uncertainty are mapped and their effects described. Method finding acceleration sensor output systematic effects and standard deviation is discussed. Data processing algorithms add additional combined uncertainty to system, which can also be estimated. An overview of calibration method and experimental results are presented and eventually further accuracy improvements suggested.