One of the best illustrations to show up on ST, and certainly most fitting was "At what point do you hide the car keys from Grampa?" I'm sorry I cannot remember who the poster was.
Where do you put Pops having access to the car or truck now?
Dangerous driver?
Accident prone?
Little fender benders nothing serious?
Harmful?
Very dangerous?
Life threatening?
DUIs? Multiple DUIs?
Has already been in numerous wrecks?