Early inquiries indicate that she was carried on the bonnet of the other car and fell from the bonnet and was in collision with a Belisha beacon. The vehicle drove away.
Police subsequently attended an address in Barnet and arrested a woman in connection with the inquiry. She was taken to a north west London police station and was subsequently bailed pending further enquiries to a date in late April.
Witnesses or anyone who has information can contact the incident room on 020 8247 7821 or Crimestoppers on 0800 555 111.
More top news
The multi-million pound company wanted 500 teenagers to work unpaid - but the chain changed its mind after being criticised on social media.
The American president insists Obamacare will 'explode' despite the humiliating cancellation of the healthcare bill vote.
Police are investigating the death of a teenager who died shortly after an amateur boxing match held last night.