However, the body of a woman inside could not be confirmed as Miss Sinclair.
Bay of Plenty police spokeswoman Kim Perks said police still needed to go through the formalities of identifying the body and letting family know.
Last night and today, police expressed serious concerns for the welfare of Miss Sinclair who was reported missing after leaving a friend's Katikati home late on Sunday night, Mount Maunganui bound.
EARLIER: The body of a woman has been found inside a car which was this afternoon discovered crashed down a bank off State Highway 2.
Police are currently at the scene in Whakamarama where the car is believed to have left the road.
Western Bay of Plenty police area commander Inspector Clifford Paxton confirmed a woman's body had been found inside the car.
"About midday today police were advised of a motor vehicle crash on SH2, Whakamarama.
"We have located a deceased female in the vehicle. Police investigations are continuing.
"A vehicle has left the road while travelling ... between Tauranga and Katikati and gone off the left hand curb.
"No other vehicle was involved."
- Bay of Plenty Times
