Riana Beech, spokesperson for ER24 emergency service, said they received a call about 07:30 on Tuesday that there was an overturned car along the R55 outside Kyalami, Johannesburg.
"The emergency staff found the seriously injured woman trapped inside.
"She said she'd been trapped inside the wreck since 23:00 the previous evening. The airbag, which had popped out while she was driving, knocked her unconscious and she lost control of the vehicle," said Beech.
The car hit pallisade fencing and moved along it for about 20m before turning onto its side.
Beech said the woman had recently taken the car, a Renault Megane, to a workshop because the airbag indicator kept lighting up.
Only victim's head, arm protruded
The workshop apparently told her there was nothing wrong with it, said Beech.
The woman was on her way home after having dinner with friends.
Beech said emergency staff and the fire brigade had battled until about 09:00 on Tuesday to free her.
"Only her head and arm protruded. She told us what had happened after she was freed," said Beech.
She apparently had serious injuries to her head, arm, leg and ankle and was admitted to Sunninghill Hospital.
Neither she, nor her family wanted to comment on the accident on Wednesday.
Pip Kruger, spokesperson for Sunninghill Hospital, said her condition was stable.