When you brake hard so the ABS is activated, the yellow hazard (rear turn signal) lights should come on to provide extra warning to the driver behind.
This may be possible by software alone, although regulations in specific countries may not allow this feature. Also USA Model S does not have amber hazard (turn-signals) in the rear, but only red lights, although the concept should work.
BMW offers this feature in some countries, called “Dynamic Brake Lights”.
The Dynamic Brake Force Display show drivers behind you how heavily you’re braking and allow them to react in good time. This drastically reduces the danger of a rear-end collision.
The brake lights themselves are divided into two zones. During normal braking, only one zone is illuminated. When heavy braking is detected, Brake Force Display increases the intensity of the brake lights by illuminating the second zone as well. In addition, the hazard lights are activated just before the vehicle comes to a standstill. The hazard lights are deactivated automatically when the vehicle accelerates or by pushing a button.