In order to estimate vehicle energy consumption and emissions, it is common to carry out a driving cycle simulation. In a conventional analysis for this purpose, the vehicle speed is prescribed to follow a function of time exactly. Such an analysis is quasi-stationary, i.e., the transient behavior of the system is not fully taken care of. The direction of cause and effect is unnatural. The opposite is a driver controlled model, where an active driver model tries to achieve the driving cycle speed by choosing a proper accelerator pedal position. Such a model requires transient analysis.Need of more accurate simulations and studies of new driveline concepts call for transient driving cycle analysis. Examples on and classification of such cases are presented in this paper. The paper also presents a DAE approach to the modelling and analysis. A DAE is a differential-algebraic equation and such an approach accepts both transient and quasi-stationary analysis and is therefore held for superior. There is numerous of commercial software supporting a DAE approach.