Constable Dean Schroder, of Cromwell, said there had been no response to an appeal for information about the collision on Friday, in which the right rear passenger door of a silver Mazda hatchback was ''opened like a tin'' and a young child narrowly avoided injury.
The collision happened between the Goldfields Mining Centre and the Roaring Meg power station, about 12.40pm.
The Mazda was travelling towards Queenstown when another vehicle travelling in the opposite direction - believed to be a white ''well-side'' ute, possibly a Toyota Hilux - crossed the centre line, Const Schroder said.
''There were other vehicles on the road and their occupants must have witnessed the incident and the driver of the Mazda did very well to maintain her path after the collision.''
''The driver of the other vehicle must have been aware of the collision - the damage to the Mazda is too significant for the other driver to be unaware something has happened.
''There must be noticeable damage to the other vehicle as well,'' he said. Although there had been ''lots of chatter'' on social media about the incident, nobody had identified the other driver.
Anyone with information is urged to contact Cromwell police.
