A koala has been lucky enough to walk away with only a few scratches after he was hit at 100km/h on a busy highway and got wedged in a car's grill.

Loren Davis was driving on the South Eastern Freeway near the Bridgewater exit, south-east of Adelaide, late on Tuesday night when a koala ran out in front of her car as she came around a corner.

Being surrounded by traffic, Ms Davis had no choice but to slam on her brakes.

A koala has become stuck in the front bumper after he was hit by a car travelling at 100km/h

The Mount Barker real estate agent said she pulled over to look out the car window to see if the animal was okay but did not see anything on the road.

She did not get out of the vehicle because it was not safe to do so as there were no street lamps along that section of the freeway and it was pitch black.

Thinking it must have run off, Ms Davis continued to drive the 10km home before pulling into her driveway.

It was there she got a bit of a shock when she spotted the koala stuck in her front bumper.

'I screamed and I ran into the house and my fiancé and stepson came out. They discovered he was alive,' Ms Davis said.

The trio called Fauna Rescue SA who came to collect the koala.

While they were waiting, Ms Davis told Daily Mail Australia they put some blankets underneath his arm to support it.

'We slid the blankets towards him and under him and he put his arm on it,' she said.

'He leaned on the blankets and pulled out his other arm and then the rest of his body. It was all pretty amazing actually.

'He was very alert.'

Loren Davis hit the four-year-old koala while driving along the South Eastern Freeway near Adelaide

Ms Davis said she was glad the koala escaped virtually uninjured.

'I feel relieved he's okay and I'm okay as well,' she said.

Fauna Rescue SA's Don Bigham told Daily Mail Australia the marsupial was fortunate to escape with minor injuries.

'This one was very lucky,' Mr Bigham, who came to rescue the koala after his accident, said.

'There was a small abrasion over the eye, but no injury to the actual eye.

'A couple of its feet had minor abrasions on it, but it might have happened in the collision or when it got out.

'There was no fractures or anything showing up on the X-ray, and the lungs looked good.'

Mr Bigham said the koala was 11.5kg and was about three or four years old.

'[Veterinarians] look at the teeth [of a koala] and his teeth were showing very little wear,' he said.

'At six years old, teeth start to wear down a little bit. He was quite a big boy.'

Despite the unusual position the koala was found in, Mr Bigham said circumstances like this were more common than people thought.

'There have been a number that we're aware of that get hit and caught up and get freed later on,' he said.

'It must have been a similar situation with a four-wheel-drive where the driver found the koala under the battery... and it survived.'