Speaking of terrible old folks driving, we're officially taking the keys away from my MIL.
She's actually still a pretty good driver, but she has dementia affecting her memory and she's no longer really capable of getting herself to and from a place, because she doesn't always remember where she was going. My i s c & a aggie wife was with her driving recently, for the sole purpose of evaluating her driving, and witnessed her become confused at an onramp and just stop in the middle of the road, forcing cars around her to take immediate evasive action.
That's when the decision was made.
She's 86, she had a good run. Luckily my FIL is still in good shape and can still drive them around.