Modern cars contain a multitude of micro controllers for a wide area of tasks. The diversity of the heterogeneous hardware and software leads to a complicated and expensive integration process. Integrating multiple tasks on fewer micro controllers reduces diversity and costs of production, but poses new problems with the growing complexity of software on a single micro controller. Therefore a more robust software development process and a safe execution environment is needed in the automotive area and other areas with similar constraints. With the KESO system we have implemented a very small and adapted Java execution environment for an OSEK/VDX operating system to address these issues. In this paper we present our approach for a low overhead OSEK/VDX system interface, which is an integral component of the KESO system. We show how access to the system services can be restricted at low cost to ensure the isolation of tasks by the use of type-safety and modern compiler techniques, while...