Forward Collision Warning (FCW) systems are intended to alert drivers to an imminent forward collision threat to reduce the frequency and severity of rear-end collisions and mitigate injury and property damage for occupants of both vehicles. This between-subjects driving simulator study examined the effects of three variables – FCW system training, auditory warning type, and gender – on a visually distracted driver's response to an unexpected, imminent, forward collision threat. First, only half of the participants were provided with a brief description of the FCW system. Second, four different auditory warning conditions were compared: no-auditory warning (baseline), average-urgency warning, highest-urgency warning, and an auditory icon car horn. Drivers who received FCW system training had faster reaction times and 68% fewer collisions than drivers who did not receive training. While the highest-urgency warning produced the fastest initial glance to the forward scene, it was the car horn warning that produced robust reaction time, glance behavior, and collision benefits. Unexpectedly, 34.7% of distracted drivers glanced back to the center console display, following their initial forward glance, prior to braking. This unanticipated behavior resulted in longer reaction times, shorter minimum time-to-collision, and a 63.7% increase in collisions as compared with drivers who did not glance back to the console display. Results suggest that even brief system training can aid interaction with an FCW system and glance behavior, reaction times can improve with an auditory icon car horn as the auditory warning, and that uninterrupted forward attention upon detection of a collision threat is imperative for an effective collision avoidance response.