The main noise sources of a diesel passenger car are determined and possible noise level reductions are assessed. Primary damping measures such as influencing it by means of modifying the combustion itself as well as secondary measures such as encapsulation are described. A vehicle-supported encapsulation of the engine utilizing parts of the body is discussed in more detail. A research vehicle was built. A description of design function, and practical realization of such a vehicle-supported encapsulation including the necessary development of a new cooling system is given. Finally, the maximum possible reduction of the external noise levels using this design as well as the problems connected with encapsulation - such as the resulting increase in internal vehicle noise and vehicle weight, reduced ground clearance and maintenance accessibility - are reported and critically evaluated.