The document presents vehicle modification use cases categorized into four cases and additional scenarios. Case 1 covers components with negligible risk or cyber-relevant non-automotive devices. Case 2 addresses cyber-relevant automotive devices approved to specific regulatory requirements, requiring installation approval and vehicle type re-approval. Case 3a addresses cyber-relevant devices not approved to specific requirements, requiring component or STU approval. Case 3b covers devices controlling vehicle functions, also requiring component or STU approval. Case 4 encompasses invasive modifications or complex interactions not covered by other cases.