My dad still thinks he is safe to drive but his sight is not great. So far, he has let me drive him around but lately he is demanding that I return his
car. I've had to "borrow" it for my son who is home from college but it has the
added benefit of keeping him away from it. He wants to drive is 2 miles up the road
to see my mom in the nursing home. I usually try and get him there 2-3 times a week and have arranged for a van to bring him on the off days I can't do it, but
he refuses to use that option.
It seems harsh but he is a danger to himself and others on the road. A few years ago I was visiting a friend and her Mother who was about 85. I was shocked to learn that her Mom was still driving as her hearing and eyesight were very poor and she had a severe curvature of the spine. My friend insisted that Mom only drove in the immediate neighborhood. Within 6 months her Mother took out a line of cars across the street and the airbag deployment sent her to the hospital where she died because her lungs had basically been crushed(not enough room in the chest cavity due to the curved spine). To this day my friend says that she should have listened to me. The important thing is that he has accessible options for his transportation needs. Good luck.
Otherwise, if your Dad no longer drives you will become his full-time driver. I've been doing that with my parents for 5 years now, and I am frazzled.
You'd be surprised how many places your Dad would want you to drive him. If my parents had their way, I'd be at their house 3 or 4 times a day to go here and there, because that is what they use to do when Dad was still driving.
Take your dad to the DMV and have him take a driving test. If he passes then give him his car back and revisit the issue in another few months. If he doesn't pass he's either going to have to get on that van or not see your mom. It's his choice.