Senior Sergeant Mark Kirkwood said the woman was found injured and disoriented and it was initially unclear whether the vehicle had had any other occupants.
Police with the help of Search and Rescue personnel and a dog checked the surrounding bush for any passengers but no-one was found.
The woman's earlier court appearance on driving matters had resulted in her being disqualified from driving and she will be now charged with more driving-related offences.
It is understood she had blood taken to be tested for possible alcohol content, and she was taken by ambulance to hospital as she had serious injuries.
State Highway 6 remained open and the crash was also attended by members of the Hari Hari volunteer fire brigade.
Whataroa fire crews were called out as well but stood down before reaching the scene.
Sen Sgt Kirkwood said she was "certainly very lucky".