When describing the transient thermal behavior of a vehicle cabin, all three heat transfer mechanisms play an important role. Three-dimensional calculation models which resolve the geometry sufficiently precise and which account for all three mechanisms are still today, even with parallelized computation, typically orders of magnitude slower than real time. The integration of a transient thermal cabin model into a thermal simulation of a complete vehicle therefore demands a reduced model, which meets the requirements regarding both computation speed and accuracy of the calculated local temperatures. In the following, an approach for such a reduced model will be presented and verified with 3D CFD simulation results. One focus hereby is on modeling heat conduction in the considered solid bodies with respect to the spatial and temporal resolution in the three-dimensional and the reduced model.