A potential application of optical looming manipulation is investigated: a dynamic brake light concept for potentially reducing the frequency of rear-end collisions in automobile driving. In a low-fidelity driving simulator, forty participants were instructed to follow a leading vehicle (LV) and appropriately respond to braking of the LV, under three visibility conditions: day, night-time with headlights, and night-time without headlights. During some LV braking events, separation and size of the brake lights of the LV were imperceptibly expanded or contracted, at one of two levels, to simulate an effective virtual time shift in the headway of the LV. Results show that this concept was effective only for very poor visibility conditions: at night with no headlights, for which LV brake lights were most salient. Subjects generally braked sooner when confronting a LV with expanding brake lights, and later for contracting lights, in comparison with the no manipulation case.