Research by Mercedes engineers has shown that driver reaction times are shortened by up to 0.2 seconds if a flashing red warning signal is given instead of the conventional brake light during emergency braking. At a speed of 80 km/h this reduces the stopping distance by approx. 4.40 metres, and at 100 km/h by no less than 5.50 metres or so. This means that flashing brake lights are an effective and easily implemented way to reduce rear-end collisions. The Mercedes-Benz S Class is now the first car to feature this innovative, adaptive brake light. It will shortly be followed by the CL-Class Coupés.

Specialists at Mercedes tested various warning light systems during their study. Brake lights which light up four times as quickly as the amber hazard warning flashers during emergency braking proved particularly effective in alerting following drivers to the danger of a rear-end collision. The Mercedes study also revealed that switching on the hazard warning system in a dangerous situation has no significant effect on the reaction times of other drivers.