It appeared the man drove into a roadside barrier, got out of the car and collapsed.
The incident happened just before 4pm on State Highway 83, northwest of the Aviemore hydro station.
Senior Constable Craig Bennett, of Kurow, believed the Mazda had drifted off the road at low speed and into the wire barrier.
The front of the car had minor damage and its bumper was left at the impact zone, almost 70m from where the car came to a stop.
Constable Jay Morriss, of Oamaru, said two passengers in the car were teenagers, a male and a female who did not require medical attention but were in shock.
"It could have been a lot worse if the barrier wasn’t there."
The barrier is between the road and a steep bank down to Lake Aviemore.
The road was reduced to one lane as emergency services cleared the scene and closed for a short time as the ambulance prepared to leave, traffic banking up on both sides.
Snr Const Bennett said passers-by offered medical assistance to the crash survivors.
No other details were available last night.
