The question of whether to drop collision and comprehensive after 80 depends entirely on your vehicle's value and your financial cushion, not your age. If your car is worth $6,000 and your collision deductible is $1,000, you're insuring $5,000 of value—but paying $60–80/month to do so. Over two years, you'll pay nearly as much in premiums as the maximum payout.
A more useful framework:
if replacing your vehicle out-of-pocket would require dipping into savings you can't comfortably afford to lose, keep comprehensive and collision. If you could write a $6,000 check tomorrow without financial stress, dropping physical damage coverage and banking the premium savings makes mathematical sense. The average driver over 80 files a comprehensive claim every 8–12 years and a collision claim every 15–20 years—your premiums are funding someone else's claims more often than your own.
Never reduce liability limits to save money.
Liability coverage protects your retirement assets if you're found at fault in a serious accident. Minimum state limits—often $25,000 per person for bodily injury—won't cover a modern medical claim. Carry at least $100,000/$300,000 in liability, and consider $250,000/$500,000 if your net worth exceeds $200,000. The cost difference between minimum limits and $250,000/$500,000 is typically $15–30/month, far less than the asset exposure.