The wing is where the car earns its "Longtail" moniker. It's primary function is acting as an air brake, and it's 50 percent larger than that of the regular 650S.
Everything else about the shape of the rear of the car is designed with the aim of moving air as quickly as possible without adding weight. That helps with downforce and reducing drag, but it also helps get as much heat out of the engine bay as possible.
Not that it's really needed. The car's already seriously cool.
Aaron Miller is the Rides editor for Supercompressor, and can be found on Twitter. He's absolutely buying one of these just as soon as he figures out how to rig the lottery.