how do i get my father to give up driving/

He has an eneurysm that is large enough that it needs to be operated on, but can't due to other health conditions, preventing the surgery. My sister and I have been successful for the last 2 years due to other health factors but he's feeling better now and wants to drive again. We've tried the "dad, i need to borrow your car for a few months.." but thats run its course. We see the dr tomorrow for more help and back up on stopping on him from driving but any other advice will help. I don't expect tomorrows dr appt to go well for my dad. Mom was supportive for a while but not as much anymore. Mom gave up driving 10+ years ago due to vision problems on her own. I have been their main person for driving them to dr appts and shopping but they also have great neighbors who help out on days I'm at work. We'd love for them to sell their home and move to a retirement community but they are not quite ready for that, but are close to being ready (cleaning out rooms in case they decide to sell sooner rather than later and starting to ask what's out there for them in the future, or if one of them passes where the other could go to live).