The heat transfer conditions in automotive exhaust piping are only recently being studied in depth because of their important role in the design and optimization phases of exhaust after-treatment systems. The complex geometry of the exhaust line and the special flow conditions complicate the problem of accurately estimating several important heat transfer parameters. This paper initially summarizes the current status of knowledge regarding heat transfer phenomena in automotive exhaust systems. Experimental data from steady state and transient heat transfer measurements in automotive exhaust systems are presented and analyzed by means of a comprehensive transient computer model covering all exhaust piping configurations (single wall, double wall with air gap or insulation) already presented elsewhere. Examples are presented, illustrating the application of the model in the comparative assessment of different exhaust configurations. In conjunction with existing models which simulate the operation of three-way catalytic converters and of other exhaust gas after-treatment devices, the model is already integrated in a CAE package for the support of exhaust system design optimization.