Who is liable when your neighbors rotten tree falls on your house or car falls on your property?

In general, Nobody is liable for an act of nature. Your auto insurance comprehensive coverage would cover damages to your car. Your homeowners insurance will cover damages to your home.

The neighbor would be liable only if your can prove the neighbor knew the tree was rotten and posed a risk. If a car falls on your property, that would mean a tornado picked it up and it fell on your home. You insurance would cover that damage.