How can I make sure I don’t make my dad angry if I talk to him about his driving?
Keep the initial conversation between you and him (no interventions). Be understanding (imagine how you’d feel if someone sat you down because they worried about your driving), and focus on finding ways to improve skills or get him to the places he needs to go. Don’t make assumptions about his ability to drive — simply having a medical condition shouldn’t result in not driving any longer. What matters is how he manages his illness and compensates for weaknesses.