Yeah, I honestly doubt that spoiler is doing much actual good. It's so far out of the windstream it's actually just affecting the eddies behind the car. That's why when VW wanted to keep their cars on the road at high speeds they used ones like the Turbo one I posted.
Then you have the Beetle RSI with its Fast and Furious type spoiler (which actually looks pretty good). It seems to reach out enough that it might help with downforce, like Porsche's whale tails did.
