Mr Mahanga, formerly of Waiomio, was now at Mohinui Marae, near Kawakawa, with his funeral planned for Monday.
Head of the homicide investigation Detective Inspector Kevin Burke said a post-mortem examination on Thursday had confirmed Mr Mahanga died as a result of a gunshot wound.
While officers continued to interview residents on William Jones Dr and surrounding streets an appeal was made to members of the public to report any sightings of a white 2010 white Mitsubishi Lancer, with distinctive black mag wheels, around Whangarei on Tuesday.
"We are following positive lines of inquiry after receiving a number of calls from the Northland community," Mr Burke said.
A floral tribute was placed at the base of a power pole close to where Mr Mahanga was discovered in the car.
There were reports of Head Hunter gang members riding motorcycles past the scene as well as a Black Power member yesterday.
Members of the Moerewa Tigers league team were to visit Mr Mahanga last night to pay tribute to their friend.
Coach Peter Prime said he had played in the team with Mr Mahanga during the 2015 season and described him as player with some pace.
"He was a jovial guy and he would put his body on the line when he was playing. He would play centre, wing or fullback and we would try and feed him the ball as he had some speed," Mr Prime said.
"He did mix with certain people but overall he was a good person."
A post on the Moerewa Tigers Facebook page read: "Our condolences go out to the Mahanga whanau at this very sad time. RIP brother MO once a tiger always a tiger spread your wing and fly high. You will be sadly missed."
Anyone with information should contact Whangarei Police Station on 09 430 4500 or contact Crimestoppers anonymously on 0800 555 111.
