The motorcyclist killed in the crash just north of Pukeuri has been named as Thomas Alec Fry (18), of Morven.
It was the second death in the family last week - Mr Fry died one day after his grandmother's funeral in Mosgiel.
Police are appealing for public help to identify the owner of the 1995 light-coloured grey two-door Nissan Skyline GTS and would also like to talk to anyone who had seen it travelling on State Highway 1, just north of Oamaru.
"A young man is dead. We want to work out how this happened and we believe that the occupants of the Skyline can help us do so," Detective Sergeant Mike Ryder said.
Police declined to comment yesterday when asked about identifying the owner of the car through registration or engine and chassis serial numbers.
Police believe the Skyline was coming from the north although it was not known where it was coming from.
They said it left the crash scene and travelled to Horse Gully Rd, about 15km inland from the crash site.
Anyone in the Oamaru area who saw a light-coloured Skyline between 3am and 6am was urged to contact police, along with anyone who might have seen it on State Highway 1, north of Oamaru, early on Thursday.
"It does not matter how far you may be from Oamaru. If you saw such a car on the road, we need to hear from you," he said.
Police had received calls from the public following publicity about the car, and there had been a particularly good response from the transport industry, Det Sgt Ryder said.
Mr Fry, who had stayed in Oamaru overnight, was heading to work on a dairy farm.
