A male driver was reportedly the first person to stop his car to try and avoid hitting the koala. His vehicle was then hit from behind, which prompted other motorists to crash.
The animal was eventually rescued by one driver, Nadia Tugwell, who was stuck behind the pile-up and got out of her car to investigate what had caused the crash.
With her coat in hand, she teamed up with a stranger, who was clutching a blanket, in a bid to capture the marsupial.
They managed to capture the koala when it was blocked by a concrete barrier in the middle of the road.
"The koala was absolutely not damaged in any way," Ms Tugwell said. "It was very active, but very calm."
Once the koala was in her trunk, Ms Tugwell drove to a gas station to give the animal to wildlife rescuers. In the interim, the koala was able to climb from the trunk into her SUV's cabin and sat at the steering wheel.
"It decided to come to the front toward me, so I said, 'OK, you stay here. I'll get out,"' she said.
"It started sitting for a while on the steering wheel: (as if ) saying: 'let's go for a drive,' and that's when I started taking photos," she added.
Ms Tugwell said she had learned from past experience how to calm koalas by covering their eyes. She lives near a eucalyptus forest outside Adelaide and has twice called animal handlers to rescue koalas injured in fights with other koalas.
"I live up in the hills, and if you let them do what they want to do and you don't chase them or something, they're OK," Ms Tugwell said.
The leather trimmings of her luxury vehicle were scratched by the animal, but Ms Tugwell said the happy ending was well worth the damage.
The koala later was released in a forest — well away from the freeway.
