The Rabbits all have the vent window - some of them were actual vent windows that opened, but I don't recall if that was the case for the GTI.

The Golf/Jetta originally came with a non-openable 'vent' window in 1985-1987 or 88, and then switched to a single big window.
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Optional across the line (except, perhaps, for a low buck carb'd Rabbit offered in '84). My '81 L didn't have them, my '84 GTi had them as a low cost option.