If you still had doubts about how useful semi-autonomous tech is in today’s traffic, this video might sway you to come around.

What the footage shows is the system saving a Tesla Model S from a side collision with a truck, but also reinforces the fact that as long as the autonomous tech stays “semi”, drivers should never, ever stop paying attention to their surroundings when behind the wheel.

According to the video’s description, the truck driver didn’t see the Model S as he was trying to get on to the exit ramp (obviously), but luckily the Tesla’s systems reacted quickly and made the car swerve to the right so as to avoid the impact.

The full story reads as follows:

“Tesla Model S autopilot saved the car autonomously from a side collision from a boom lift truck. I was driving down the interstate and you can see the boom lift truck in question on the left side of the screen on a joining interstate road. Once the roads merged, the truck tried to get to the exit ramp on the right and never saw my Tesla. I actually wasn’t watching that direction and Tessy (the name of my car) was on duty with autopilot engaged. I became aware of the danger when Tessy alerted me with the “immediately take over” warning chime and the car swerving to the right to avoid the side collision.

You can see where I took over when there’s a little bit of blip in the steering. Tessy had already moved to the right to avoid the collision. I was not able to slow down even more due to the heavy traffic (cars were behind me). Once I got behind him I slowly added more room between us until he exited. I was not tail gating after the incident.”

The owner of the car also goes on to say how impressed he is with the car, and even apologizes for the poor video quality, but the gist of it is this – don’t take your eyes off the road. The Model S is an almost-autonomous car, with “almost” or “semi” being the key word.

Still, the tech itself scores major points for making this save.

VIDEO