Do German universities internally track the scientific output of single work groups/professors and with which internal/external goals? We are asked in our group to send new publications for journals and conferences  to our secretary, who told me she has to input this information also into a database of the university. Over the years of PhD/Postdoc my Professor also seems to favor publishing many small papers rather than leaving it to the first author to make a decision on splitting up research results. This sometimes leads to conflicts, as the goals of my professor, my university and researchers without permanent positions can be different as the strategies to realize them.

So, I'm wondering if this kind of quality management/evaluation of the publication output is used by the administration to reward very productive groups and if so, by which kind of number games and really in financial rewards (increasing budget etc.)? (Number of Articles) x (impact factor)...
I would ask your professor, other professors, or people you know in the administration. Presumably, they know how these evaluations are done in your University.

My experience, in a research institute in Germany, is that faculty is evaluated on both output and grants obtained. Similarly, the institute as a whole is evaluated on these points. Typically, professors try to publish as high as possible here, with much less regard for number of papers published. This is reflected in tenure decisions.