My husband has been diagnosed with “vascular dementia with Alzheimer’s features”, first diagnosed with “minimal cognitive impairment” 8 years ago, following neuropsych testing. My journey is your journey, except we are further down the path.
Please consider this suggestion- find the registration for your car and make sure it is jointly owned. If not, you take it to AAA or somewhere else, get the form to change it to jointly owned, and sign his name yourself. Here in PA, my husband wasn’t required to be there in person to add me.
Then when it’s time to stop driving, you alone can quickly take the car back to the dealer you bought it from, sell it to them (they’ll let you sign his name) and buy another one (unless you already have your own car). He will be mad, but blame it on the doctor. If you keep “his” car, but with you driving it now, this will make him really mad every time it’s time to go somewhere. He will say the doctor is wrong, you are wrong, etc, etc. If you change to a “new” car, he will not feel “ownership” that you are interfering with by being ridiculous.
Next step- go online to your state’s Department of Motor Vehicles or Dept of Transportation and print out the form for surrendering your drivers license due to age or medical reasons (I printed it out at the Library- he wants to see what I’m doing online). Fill it out and mail it in with the license (get that quietly out of his wallet) and they will mail you back an ID card that looks like the drivers license and uses the last photo he had on his. It’s free in PA. This completely avoids the “hand it over” symbolic nightmare. If he notices it’s gone before the ID comes, just say, “I don’t know, but I’ll order you another one”. The PA ID looks very similar to the DL. Then it can be, “Oh, they sent this one instead, the doctor must have told them no more driving for now.” I often use “for now”- my husband accepts that much more easily than “you can’t”. This was his PCP’s idea.
This may sound to you or others as “under-handed”, but the focus HAS to be on what will work, what will keep you and others safe, what will avoid the tornado of fury from someone whose brain is unable to operate and process information as before.
Finally, please consider consulting an “Elder Law” attorney- Google for “near me”, go quietly yourself. They have an extra certification and know the ins and outs of your state’s laws and can guide you to protecting both of you, for the future. It is really, really worth it.
Daily life is a challenge, but I focus on what works now that dementia has moved into our house 🤣 It is hard to let go of the way things used to be.

For what it's worth, when my husband was not able to draw the time on a clock - 10 to 11, the neurologist said that was the indicator that he should not be driving anymore. He had gone through a STOP sign that same day so I didn't argue. Ian gave up driving willingly, which was a relief since I didn't have to watch him so closely anymore. Now he sits beside me, enjoys the scenery, and compliments me on my driving, with occasional instructions.. Our state is self-reporting - so when his driver's license expired he got a state ID instead.