Do you know anyone with an ozone generator? That's what I'd use to get rid of funky smells in the upholstery, headliner, air vents, etc. And shampoo the carpets and change the cabin air filter if your car has one.
Fleet Farm sells a product in the dairy chemicals aisle called Steramine. It's 10% benzalkonium chloride; about $17 for a gallon. It's basically a hospital disinfectant and kills molds, bacteria, and even viruses, and replaces odors with an oddly "fresh" smell that goes away after a while. It might be worth spraying the carpet and the seats with some of that, diluted about 100:1. Don't get it in your eyes, other than that it's pretty nontoxic.