This form of dementia makes it impossible for his brain to perceive there is anything wrong. Thus all attempts to get help like Visiting Angels or a caregiver are met with complete refusal and dismissal because he is "just fine." He is still driving (!) and really should be in a home or have a caregiver. Is the only answer to have his daughter get guardianship through the court and then make a decision to move him against his will? He will never understand there is a problem.
I would start with questioning APS who may be able to help you in getting Temporary guardianship if person is (and he IS) a danger to self and others.
He is never going to accept he has dementia, so give that up.
I would advise you to read, Google and learn anything and everything about dementia you can.
You need to find a way to get the keys away from him. That's utmost important!!!!!
You cannot convince someone with anosognosia OR dementia of anything, so stop trying. His daughter needs to do what you said, or report him to APS as a senior with dementia living alone and THEY will place him. But in the meantime, his car MUST BE REMOVED. Please do the right thing.