Following directions could save your life—especially behind the wheel of a Tesla Model S on Autopilot.

The vehicle maker last week rolled out a software update that added an Autopilot functionality to newer Tesla vehicles. It's not completely autonomous, but allows cars to steer, switch lanes, and manage speed on their own.

"The driver is still responsible for, and ultimately in control of, the car," Elon Musk said during last week's announcement.

One Tesla owner learned that the hard way. Using his hands to film the experience (watch below) instead of holding the wheel of the car as advised, the driver felt his car veer toward oncoming traffic.

"Had I not reacted quickly to jerk the steering wheel in the opposite direction, a devastating head-on collision would have occurred," he wrote in a YouTube post, urging other Tesla owners to stay focused.

Another video highlighted an Autopilot-equipped Tesla taking the wrong freeway exit, but it stayed in its lane. Tesla has said that the more you drive, the better Autopilot will get.

Rally race driver Alex Roy, for example, completed a 2,700-mile trip from California to New York in 57 hours and 48 minutes—behind the wheel of an Autopilot-enabled Tesla Model S.

Autopilot makes use of four sensors: ultrasonic sensors around the perimeter of the car to detect obstacles; a forward-facing camera with image recognition that sees lane marking and signs; forward radar that can detect large objects and navigate through bad weather; and GPS with high-precision maps for navigation.

About 60,000 Tesla vehicles can take advantage of Autopilot, though it will set you back $2,500. Whether you pay or not, though, the version 7.0 update equips all owners, paying and non-paying, with safety features like emergency braking and side-collision and lane-departure warnings.

For more, see PCMag's review of the 2015 Tesla Model S P85D and a test drive by our sister site IGN in the video below.