Fast changing irradiation on vehicle-integrated photovoltaic (VIPV) modules may impose demanding requirements for maximum power point tracking (MPPT) to ensure high energy conversion efficiency. In this work, the results of simulations regarding the output and efficiency of an exemplary VIPV module under real-life irradiation conditions as measured with high time resolution are resulted. Herein, resistive as well as voltage source load is used as two idealized models of the MPPT. The simulations show that, in most cases, tracking with a resistive load at 1 Hz preserves above 90%rel of the convertible energy determined by the cell performances under given irradiance levels. With a voltage source load, these values do not undercut 97%rel at 0.1 Hz. Herein, it is also found that partial shading across the exemplary series connected module can reduce the converted energy in the range of 5–10%rel in relation to complete negligence of this effect.