An algorithm that is part of a collision preparation system that provides selective and limited vehicle braking to avoid undesirable intrusive high-G braking while still giving the system adequate time to activate collision mitigation devices on the vehicle before impact with an object. If a predicted time to collision between the vehicle and the object is less than a required time to collision, which is determined by how much time is necessary for a certain collision mitigation device to be activated, the algorithm calculates a time dilation deceleration. The system causes the vehicle to automatically brake to decelerate the vehicle at the time dilation deceleration until the time dilation deceleration reaches a predetermined decelerating threshold so that more time is available for the collision preparation system to determine whether to activate the collision mitigation device.