Cat Piss.
I feel your pain. Left my 70 bug at worked over night once, forgot the window was down.
Next morning, cat spray, piss and hair.
I took all the soft surfaces out and tossed them. Cleaned up what I could reach and peppered the car with baking soda.
Don't know the wisdom of my choices, but after a month or so I did not notice the stench any more. The seat springs were a bit hard on the back side! :realcrazy: