My grandma drove until she was about 94. I can SO relate.
One time when she was 93, her and my aunt (75 at the time and blind in one eye from a brain tumor with a cataract on the other eye) decided to drive from St Pete FL to Columbus OH. Talk about frightening. I was certain I was going to see the 25 car pile up on CNN from my grandma driving 50 in the left lane but much to my surprize and relief they made it!!