Yikes! Other than selling the car to a Vietnamese family, my suggestion would be to look for some Nature's Miracle:
It's found at most pet stores and places that sell cleaning products. It has enzymes that break down odor causing agents of biological origin, such as saliva, urine, vomit, and feces. Fish sauce is pretty organic, so I suspect it will work on it as well. I used it years ago in my 1994 Suzuki Sidekick when my then girlfriend vomited white wine and seafood dinner all over my passenger seat.