The red Toyota Corolla hatchback was hired from a central Auckland rental firm just before lunchtime on Sunday, the day after Ms Millane was last seen alive.
A full scene examination is underway in a bush area on Scenic Drive, in West Auckland.
CCTV image from December 1 shows the last known sighting of Grace Millane whose 22nd birthday was the next day.
Detective Inspector Scott Beard told reporters near the crime scene in the Waitakare Ranges that police believe Millane's body was taken to the area in a rental auto that was later left in the town of Taupo.
Grace Millane (pictured), from Essex, was on the second leg of a year-long trip around the world after graduating university.
A stretch of the road has been closed while investigators search the area, which Det Insp Beard said would be a "methodical and slow process".
The detective appealed for anyone who saw the vehicle in the west Auckland area between 6.30am and 9.30am on Monday to come forward. He is due to make his first court appearance on Monday.
"We will be pleased to be giving Grace back to her family", Det Insp Beard said.
NZ POLICEGrace Millane was captured on CCTV footage at Sky City on December 1
Police are questioning Ms Millane's suspected Tinder date over her murder, The Sun reports.
Millane had been in New Zealand for two weeks, the UK's Press Association news agency reported.
Speaking from the scene, he said it was an unbearable time for her family and his heart goes out to them.
Police said her family were "devastated" after being told the missing persons case had become a murder investigation.
He's pleased however to be able to give Grace back to her family.
Last night, police announced that a 26-year-old man had been charged with her murder.
Her other belongings had remained this week at Base Backpackers, where she had been booked in to stay until today. However, police said several of her possessions, including her passport, are missing.