This paper analyses the thermal loading of damping elements in passenger vehicles caused by vertical oscillatory excitations for both conventional internal combustion engine (ICE) powertrains and electric powertrains (EM). A simplified oscillatory model with three lumped masses is applied, comprising the unsprung mass, the sprung mass, and the powertrain mass. The excitations originate from road micro-irregularities and from inertial forces of the power unit, for which representative analytical models are adopted for both powertrain types. By numerically solving a system of nonlinear differential equations, relative velocities and forces in the damping elements are obtained, on the basis of which the dissipated mechanical energy, i.e. thermal power, is calculated. For comparative analysis, RMS values of thermal power are used, together with frequency-domain analysis employing partial coherence functions. The results show that thermal loads are highest in the tyres and lowest in the powertrain mounts. In the case of electric powertrains, lower thermal loads are observed in the suspension damping elements and powertrain mounts, whereas in vehicles with conventional powertrains lower loads occur in the tyres. It is concluded that the energy aspect of oscillatory processes represents an important design criterion in the conceptual vehicle design phase.