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I'd bet it's battery acid. Your battery drain hose could be damage from the prior frontal collision. A simple test with pH strips will give you a quick confirmation. Work with rubber gloves and eye protection.
I'll chase this down, as odor does remind me of acid from what I can recall from my chemistry classes. Think I'll take @dgjks6's suggestion and use some baking soda to see if I can get a reaction for a quickie test.
Did you pull all of the carpet off? Keep it off and drive around to see if you can spot any leaks. It could be your brake mc, windshield washer reservoir, abs motor.