The reforming of short-chained hydrocarbons up to gasoline is a well-engineered process. Reforming Diesel fuel is more difficult due to the multiplicity of long-chained hydrocarbons and different components. However, the automotive market segment for Diesel vehicles is very promising for applications like auxiliary power units. Due to decreasing sulfur contents in Diesel fuels, the usage of catalytic reforming processes becomes more feasible. Commonly favored gas process technologies are the steam or autothermal reforming processes. Applications with PEM fuel cells require a complex gas cleanup system. Hence the overall size of this system tends to be rather big. Applying an autothermal reforming process is almost state of the art, although the influence of fuel composition and additization is not well described.