Inquiries into the whereabouts of the murder weapon are also ongoing.
The investigation team were keen to speak to anyone that saw the 2005 model silver Ford Falcon XR6 Saloon, registration CRL12, in the Pahiatua and Woodville areas between 7am and 3pm on Sunday.
Police had previously said that they understood Mr Whatuira had travelled to the Ormond Street address in this car.
"I want to thank those vigilant members of the public who have called in with information as well as media for helping us with our appeal," Mr Harrison said.
"From the calls we have received it is evident that the public are keen to help us solve this investigation and bring some relief to Mr Whatuira's grieving family.
"We still want to speak to anyone that has any information, including sightings of the silver Ford Falcon vehicle and we encourage them to speak up and contact Police."
Anyone with information is asked to contact Detective Constable Claire Adkins on (06) 210 2201. Information can also be provided anonymously to the organisation Crimestoppers on 0800 555 111.