Still, "Full Self-Driving (Supervised) requires you to pay attention to the road and be ready to take over at all times," the manual states. "Failure to follow these instructions could cause damage, serious injury or death." Now, however, new in-car messaging urges drivers who are drifting between lanes or feeling drowsy to turn on FSD—potentially confusing drivers, which experts claim could encourage them to use the feature in an unsafe way.