Synthesis of automotive architectures is a complex problem that needs an automated support. AUTOSAR, standard for the specification of automotive architectures, defines a synthesis process of software components and their connections in a set of fixed-priority OS tasks distributed over a network of ECUs. During the synthesis process software components are allocated on ECUs. Since each component encapsulates a set of so-called runnable entities, synthesis completes by partitioning runnable entities in OS tasks with assigned fixed priorities. This paper proposes an optimization approach for the synthesis of AUTOSAR architectures based on genetic algorithms and mixed integer linear programming techniques. Optimization criteria consider end-to-end timing responses and memory consumption.