  Vehicles passengers and other traffic participants are protected more and
more by integral safety systems. They continuously perceive the vehicles
environment to prevent dangerous situations by e.g. emergency braking systems.
Furthermore, increasingly intelligent vehicle functions are still of major
interest in research and development to reduce the risk of accidents. However,
the development and testing of these functions should not rely only on
validations on proving grounds and on long-term test-runs in real traffic;
instead, they should be extended by virtual testing approaches to model
potentially dangerous situations or to re-run specific traffic situations
easily. This article outlines meta-metrics as one of todays challenges for the
software engineering of these cyber-physical systems to provide guidance during
the system development: For example, unstable results of simulation test-runs
over the vehicle functions revision history are elaborated as an indicating
metric where to focus on with real or further virtual test-runs; furthermore,
varying acting time points for the same virtual traffic situation are
indicating problems with the reliability to interpret the specific situation.
In this article, several of such meta-metrics are discussed and assigned both
to different phases during the series development and to different levels of
detailedness of virtual testing approaches.
