9. Go nuclear
If, after everything else, that smell's still there, it's time to push the button: blast everything in the car with high concentrations of ozone. Ozone is an oxidizer, which means it’ll rapidly increase the reaction that’s causing the smell, effectively using up the smell’s fuel supply.
But don't use those worthless ionizers you see on TV. Rent a proper ozone generator—the kind that can make your car an extremely unpleasant environment for any living thing. Seal off your car, and pump it full of the good/bad stuff for 30 minutes. Any longer than that can actually age your car's interior.