The family of a former Dunedin man whose car was found at a well-known walking track in West Auckland are urging the public to come forward with information.

Sam Newton-Jones, a 33-year-old PhD student, was last seen at his workplace in Henderson on Tuesday.

Police said his car was later found at the Mercer Bay Loop carpark near Piha but there was no sign of Newton-Jones.

Newton-Jones's family said he was a much-loved son, husband and father-of-two, and his disappearance was "deeply concerning".

Police wanted to speak to anyone who had seen Newton-Jones walking on the track or in the Piha area on Tuesday afternoon or evening.

A spokesperson said Newton-Jones also visited the track on the morning of October 19.

"Members of the public may have noticed him in the area on that day, and we would like to hear from them."

A statement from Newton-Jones's family said he was "warm, empathetic and incredibly generous".

"He plays a significant role in the lives of his family and friends. They are deeply concerned that he is missing."

Newton-Jones was born in Dunedin and worked for Fulton Hogan in the city and later as a junior water engineer at Central Otago District Council.

He decided in his mid-20s to re-train as a psychologist.

"He is currently in the final stages of completing his PhD. He has a passion for working with children and young adults and helping them to navigate adversity.

"Like many New Zealanders, Sam has experienced his own mental health challenges. However, he recently described himself as feeling optimistic about the year ahead."

The family said his disappearance is highly out of character.

"Sam's family urge members of the public to contact police with any sightings, observations or information that may help to locate him.

"Sam's car was last seen at Mercer Bay, so Piha locals in particular are asked to stay aware of Sam. The family appreciate prayers and support at this difficult time."

Newton-Jones was about 185cm tall and wears glasses . He was known to be wearing a white shirt, black pants and black sneakers.

Anyone who had seen Newton-Jones and had information on his whereabouts should call 105 and reference 261020/5431.