Method and device for operating a combustion engine

The invention relates to a method and a device for operating an internal combustion engine, in particular for commercial motor vehicles, with a fuel supply device and a downstream exhaust system, wherein in order to achieve an improved efficiency, the exhaust enthalpy in the exhaust gas stream of the internal combustion engine (1) is utilized to operate a heat engine (6), in particular a Stirling engine, which generates mechanical energy.