Dealing with multiple models for process assessment and improvement is a challenging, time-consuming task. In the automotive sector, for example, several suppliers drive their process improvement on the basis of CMMI. However, many car manufacturers require process capability ratings determined on the basis of Automotive SPICE. An approach is presented toprepare Automotive SPICE by making extensive use of the work already performed to align processes to CMMI. The approach was already successfully applied in industrial settings and lessons learned are discussed. The approach helps to avoid misunderstandings during assessments due to different model taxonomy, achieve appropriate process ratings, and save both effort and costs.