What an ordeal.. Also, never let a fat friend get stuck in your passenger seat and knock over a milkshake into the seam of the seat cushion and back. It stinks.
This sounds odd, but as far as I know the two best stench removers are pine oil and lemon juice. Not combined, of course.
I've had success with the pine oil in stinky old cabins, but that was being mopped onto the floor.
My idea is to leave a dish of lemon juice on your dashes (front and back) and allow them to completely evaporate. This will saturate the air with lemon scent and acids, which can remove many horrid smells. They (or more concentrated extracts) will fix the smell of rotten food, motor oil, tar, and even dead things.
My 2 cents.
-Will
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1990 740 Turbo, on its way to stock specs, maybe beyond