I had to do all of this with my WWII-veteran grandfather in his last 5 years. He was fiercely independent but started having more and more "car issues". I can give you some awesome stories another time (some funny, some "oh shit"), but no matter how hard we tried to convince him (including me "anonymously reporting him" to DPS and them forcing him to take a driving test - WHICH HE SOMEHOW PASSED!), it was just like your dad ... it wasn't until *he* decided and accepted his limitations that he stopped driving.
"Helping" him in his last 5-10 years was probably the greatest thing I've ever done, short of raising two good citizen kids. While it was tough, challenging (from him more often than not!), and a definite impact on life for me ... I would not have changed a single second of it. I would swing by after work several days a week and just hang out. A lot of the times, he'd have the channel with "Andy Griffith", or some western on, and he'd fall asleep in his chair for 30 minutes.
I miss that old guy ... he was my hero. I strive to be half the man he was.