Shocking dashcam footage has captured the moment an out-of-control Tesla narrowly missed oncoming traffic on a busy Adelaide freeway.

The footage, captured on the South Eastern Freeway yesterday, shows the car nearly missing several others as it hurtled down the wrong side of the road.

Police are investigating whether the driver suffered a medical episode.

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The footage, first posted to Dashcams Adelaide Facebook group, showed the seconds before the Tesla crashed into a barricade.

The force of the crash forced the car to slam straight into a family.

"I would say if we were a quarter of a second faster or didn't brake then we probably would have taken out the Tesla driver," the driver told 9News.

There are no reports of any major injuries.

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