Advanced Driver Assistive System (ADAS) technologies have been introduced as the automotive industry moves towards autonomous driving. One ADAS technology with the potential for substantial safety benefits is forward collision warning and mitigation (FCWM), which is designed to warn drivers of imminent front-end collisions, potentiate driver braking responses, and apply the vehicle's brakes autonomously. Although the proliferation of FCWM technologies can, in many ways, mitigate the necessity of a timely braking response by a driver in an emergency situation, how these systems affect a driver's overall ability to safely, efficiently, and comfortably operate a motor vehicle remains unclear. Exponent conducted a closed-course evaluation of drivers' reactions to an imminent forward collision event while driving an FCWM-equipped vehicle, either with or without a secondary task administered through a hands-free cell phone. Participants drove the vehicle along the test track at a speed of 35 mph 40 feet behind an inflatable target vehicle, which was towed behind a truck and, unbeknownst to drivers, released at one point during the drive to simulate a sudden lead-vehicle braking event. Despite the relatively high speed and short headway, 14 of 16 participants were able to respond before the autonomous braking system engaged. The audiovisual collision warning system activated for 11 participants; of these, 7 reacted before the warning began. These preliminary results indicate that although ADAS technologies, specifically FCWM, can be effective tools to mitigate the risk and severity of a collision, attentive driving continues to play an essential role in roadway safety.