Guoquan Wu, also known as Laurence Wu, hasn't been seen since March 10 on Sainsbury Rd, in the suburb of St Lukes. His vehicle - a Hyundai Santa Fe with the licence plate number GSE162 - was found at Piha Beach car park two days later.
The 22-year-old University of Auckland student's parents and brother, Lucas, flew to New Zealand from the family's home city of Guangzhou, in China, shortly after his disappearance.
But so far searches have been unable to find Wu.
"Over these past months, our family has faced the most difficult, toughest and painful times with the disappearance of Laurence," brother Lucas Wu wrote today.
"We would like to seek closure to this investigation."
To do this, the family was offering a $200,000 reward for anyone who can find Wu or his body, or "provide sufficient evidence and help us to find him or his body".
"We are hopeful that once the public sees the news, someone can provide critical or accurate information that will help us find Laurence Wu."
At the end of March after three weeks searching for Wu, his brother Lucas earlier told the Herald his family had felt "helpless".
"We've been to Piha many times. We checked every place he might be, but so far we've found nothing. We've also checked the university, the casino, internet cafes, clubs."
Wu had broken up with his girlfriend recently, and she told the family Wu had said he was going to Piha to "clear his mind".
However, the family did not believe Wu had deliberately harmed himself, Lucas Wu said.
"He's a funny and outgoing person."
Police confirmed they had received an email offering a $200,000 reward for information that led to his discovery.
Earlier in March, police said they were still "conducting a number of lines of inquiry" into Wu's disappearance.
