This color was chosen to designate a car controlled by an autopilot
Mercedes-Benz was the first in the world to introduce turquoise side lights into its cars. The company received the appropriate permission from the US regulator, but it is currently valid only in two states (California and Nevada), since the innovation has not yet been enshrined in law.
Why did you need to change the regular color lights to turquoise? The thing is that this color will be used to display the operation of the automated driving system. That is, seeing turquoise side lights on a car driving nearby, the driver will understand that the car is being controlled by an autopilot. This is especially important for the German automaker, since Mercedes-Benz was the first in the world to certify its Level 3 autonomous driving system. It does not require you to keep your hands on the steering wheel and constantly watch the road.
Turquoise marker lights are included in the industry standard SAE J3134, so as self-driving technology advances, they will be implemented on other brands of vehicles.