Thermoelectrics provide a way of recovering thermal energy in the vehicle. However, the combination of classic heat exchanger and thermoelectric material integrated into the vehicle environment results in high demands on dimensioning the thermoelectric generator system. Without detailed analysis, this prevents the thermoelectric system from providing any sufficient benefit. This paper discusses simulation results generated using a simulation structure adapted to suit thermoelectrics. The investigations carried out are presented on the basis of multi-channel thermogenerators for a gasoline-engined vehicle. Three abstraction levels exist within the overall model environment that are used as required during the dimensioning process. To begin with, a rough configuration is defined in a series of steps on the basis of a continuous model. Although this abstraction level provides the capability of computing many different variations, it proceeds from a highly simplified basis. CFD simulation and FE simulation represent the levels with the highest degree of detailing. They serve as verification of the results from the higher abstraction levels. A simulation environment exists between the abstraction levels presented that is a compromise between the environments described. This models the system fairly accurately while requiring computing times that still permit an analysis of different variants. The design process finally produces three thermogenerator variants that perform in the targeted way. These are examined and assessed under various aspects at the end of the paper. The summary shows the most favorable system under the specified boundary conditions.