There's no stability issue with the wing disconnected on windy or rough roads. I drive a lots in WI where there are plenty of open stretches and twisties. It may help on a race track but on public roads it is more than useless. It evens block the rear window along the bottom.

Tha Porsche wing has a 'boot' to cover the mechanicals, so it doesn't look like a wing from Pep Boys. Favorite Porsche - 1967 911s - no wing.