Mercedes has come up with something cool.... again! (gotta credit them with the invention of the car, with an internal combustion engine, right?) it's rims, with electrically controlled vanes that actively adjust for aerodynamic drag reduction, or max brake cooling air

the wheels incorporate active aero. 

The vanes reposition themselves based on the car’s drive mode.

When aiming for efficiency, they close off to reduce drag.

For performance, they adjust to allow better air flow to the brakes. 

Individual generators powered by the wheels provide the electricity to run the tiny actuators mounted in their hubs.

https://www.thedrive.com/news/the-mercedes-amg-gt-xx-concept-has-active-aero-wheels-and-1341-hp