I've always seen this under my car when doing my oil changes, but I've never known what it was. It's a black piece of plastic connected to thin sheet metal that goes up behind the engine. I grabbed a screenshot from a YouTube video to show what I'm talking about. It's right above the guys head.

 

Drip spout for condensation from the air conditioner? That's my guess.

 

I don't think it is for the condensate drain. I looked briefly at mine doing my oil change, but didn't bother to trace it back up the engine. I am thinking it has something to do with the turbocharger where it either vents or intakes air for cooling.

 

I believe that's the downdraft jet for "hover mode." You have to very careful when activating this feature, because if you get the sequence wrong, the passenger seat ejection function can be activated by mistake.
These features are a dealer-installed option. I was so excited to have it offered to me for only $6,000 extra by the helpful guy in the Finance office. He said they don't offer this package to everyone -- only special customers. Boy did I feel special, though I have yet to actually try hovering. Afraid I might activate the ejection function by mistake.

 

Yep. “Air-discharge duct for turbocharger”. Part number. 11658605502

Part of the turbo heat shield assembly.

 

Well..... maybe it's dual function. I'd hate to think I'll have to live my life without the hover function.

 

It activates during typical 'overboost' situations...makes perfect sense to me! Just be careful of cross winds when approaching overboost/hover mode, you don't want to drift into the neighboring lane or oncoming traffic...