A koala has been affectionately dubbed "Bear Grylls" after it became wedged in the grille of a vehicle travelling 100 kilometres per hour in the Adelaide Hills.

The koala was hit on the South Eastern Freeway and remained stuck until the driver arrived home some ten kilometres down the road.

Driver Loren Davis said she hit the koala just after the Bridgewater exit heading to Mount Barker, where it was dark "with no street lights".

"I didn't see the koala until my headlights found it but I couldn't change lanes because another car was there [on the inside lane].

"I slammed my brakes on but another car was behind me, so there was no choice but to hit the koala."

Ms Davis said she pulled over after both cars had passed but could not see the koala in the dark.

"I drove home, feeling upset that I'd killed a koala.

"Once I got home and pulled into the garage I turned on the light to see the damage.

"I turned around, saw a koala and just screamed."

Ms Davis said she thought the koala was dead and ran inside to tell her fiance and his son.

"When they called out and said, 'he's alive', I was teary, thinking of this poor koala in the front of the car."

Ms Davis said the koala seemed quite "with it" and growled every time they drew close.

They were able to push a blanket underneath its arm and the koala used it to pull himself out of the grille.

"We backed my car out and closed the garage door to let him rest in there. We didn't want him to wander off until we'd seen he was okay.

"We're calling him Bear Grylls."

Michael 'Bear' Grylls is a British adventurer and television presenter with a knack for getting himself into dangerous situations and surviving unscathed.

CFS considered to remove the koala

Fauna Rescue of South Australia volunteer and koala hotline operator Don Bigham said the owners of the car talked about calling the Country Fire Service to remove the koala.

The koala crawled out of the grille and despite its ordeal, was diagnosed with only minor abrasions. ( Supplied: Michael Hughes )

Because it would take him 40 minutes to get to the house, Mr Bigham suggested they call the Royal Automobile Association.

"But fairly quickly, the koala got out," Mr Bigham said.

"They had closed the [car] garage when they got home, so they had it [contained].

"When I got there it was sitting on gym equipment with some obvious minor abrasions."

The koala was taken to a vet where x-rays and a further examination was undertaken.

Despite the ordeal, the koala was mostly uninjured, suffering only abrasions.

"The koala has come home with us and probably in the next day or so it will be going back home," Mr Bigham said.

Koalas are a regular occurrence on Adelaide Hills' roads and often display a casual disregard for traffic conditions.

"They don't behave in an extremely bright manner sometimes," Mr Bigham said.

"They walk down the middle of the road, [even] sit on roads."

Second 'grilled koala' in three weeks

A koala poking out from the front of Rachel Allgood's car was an unusual sight as she pulled up in her Adelaide driveway. ( Supplied: Rachel Allgood )

Three weeks ago a different koala hitched a ride in the grille of a car travelling about 80kph on Lonsdale Road in Adelaide's southern suburbs.

Driver Rachel Allgood had just shifted from the 100kph zone to the 80 zone while travelling home from work when she spotted the animal in the middle of the road.

She could not swerve due to being surrounded by cars and had no choice but to hit the animal, and did not expect it to survive.

When she returned home she heard unusual sounds coming from the front of her car and found that the koala had tumbled head-first into the car's lower air intake.

"His head was totally lodged into my grille," Ms Allgood told 891 ABC Adelaide.

"I was stunned, I did not know if it was okay and was a bit too scared to go near it."

Her neighbour removed the koala and the marsupial jumped over a neighbour's fence and scaled a tree.

Ms Allgood called a koala rescue organisation and within two hours the animal was in their care and the koala was taken for vet checks.

Several days after the incident, it was discovered the unexpected passenger had managed to do considerable damage to the car.

"About five days later I was driving home from work and the temperature gauge started to climb quite quickly," Ms Allgood said.

"I had a message coming up saying the engine was overheating, so I pulled over quickly.

"There was radiator fluid going everywhere."

With her car now repaired and the koala safely relocated, Ms Allgood said she still felt a little nervous driving along the same stretch of road each day.

"I definitely think about it every time drive along that road now," she said.