[int_19h]

Even if you won't prevent the collision, reducing the velocity at which it happens is still very desirable, And, given that kinetic energy of the car is proportional to velocity squared, even a little bit of reduction means a lot less energy dumped into the pedestrian.

[bryanlarsen]

Sure, if you've hit the brakes by then. The reaction time delay means you travel significant distance before hitting the brakes.