The stringent safety requirements of the automotive industry necessitate compliance with standards like ISO 26262. Processor cores, often pre-certified to ASIL-B or ASIL-D, face certification risks when modified. This work focuses on the development of custom instructions that are integrated through Codasip’s Bounded Customization (BC) without directly modifying the core’s verified RTL. The paper details a workflow for this process and presents performance results demonstrating the acceleration achieved for key automotive and DSP algorithms, including Field Oriented Control (FOC). All extensions were consolidated into a unified custom processor, termed as the Motor Control with DSP (MCXD) core, featuring a scheduling algorithm that coordinates FOC and filtering routines. Synthesis showed an area increase of ~31%, while runtime and instruction count measurements demonstrated performance improvement of up to ~21%. These results validate that domain-specific acceleration can be achieved within the boundaries of ISO 26262.