Cat Piss.
After you do all the spraying and wiping you can, buy a bag of plain charcoal, split it open to expose the charcoal and leave it in inside the car with the windows rolled/up. My friend got this tip from the funeral home director; he needed to make his brother in law’s garage smell better after the brother in law didn’t check in with family for two weeks during a hot texas summer. He said it 100% cleared up the smell. But, cat piss could be worse, I dunno.