This was seen as a problem in Formula 1 when they moved to hybrid engines - and so when a Formula 1 car is engaging regen during braking for a corner the red li

This was seen as a problem in Formula 1 when they moved to hybrid engines - and so when a Formula 1 car is engaging regen during braking for a corner the red light they have on the back of the car flashes to let any car following know that they are likely to stop faster than if just using brakes alone.