It's hardly just cars. They have similar lifespans in areas that aren't so car-centric.
They get parasites. They get into fights with animals in their weight class (like racoons). They get trapped by animals outside their weight class (like wolves). Tons of issues in the wild.
My uncle has a farm with a bunch of feral cats around. I learned at a young age to never get too attached to outdoor farm cats.
Thinking isn't your strong suit.