They could not move in the smoke-filled car while other motorists - including by fortunate chance Waitaki Rural Chief Fire Officer Eric Spittal - used fire extinguishers to fight the fire at Hilderthorpe, about 14km north of Oamaru.
However, the fire kept reigniting the engine bay, a rear tyre and grass, but the couple could not be rescued because of the 11,000kV and 240V power lines draped over the car.
The Oamaru Fire Brigade arrived just as the fire extinguishers ran out, and after 15 minutes, firefighters realised the trapped pair were having trouble breathing.
They then decided to shift the power lines using a fibreglass hook, so the couple could be rescued.
"I've never seen anyone come out of a car so quickly," Mr Spittal said.
The couple, from Waikouaiti, were initially taken to Oamaru Hospital.
The 25-year-old man was later transferred to Dunedin Hospital suffering from smoke inhalation and chest pains.
The 23-year-old woman was treated in Oamaru for seat-belt bruising and abdominal pain.
Mr Spittal, who was returning to Oamaru after issuing a fire permit, did not see the crash, in which the southbound car left the road and hit the concrete power pole just north of the North Otago Hotel and Motels.
He arrived "a few seconds" after the crash, grabbed a dry-powder extinguisher from his vehicle and helped fight the fire.
While Mr Spittal instinctively put decades of training into action, he thought he was going to die when he stepped on to wet grass.
"I went under the lines and as soon as I hit the wet grass, I started to get [a shock]."
He managed to get back on to the sealed road and joined others fighting the fire.
They shouted to the two occupants to remain in the car and not move - both would have been killed by electric shock as soon as their feet touched the ground.
"If we tried to pull them out, we knew we would die," he said.
"My mouth was so dry I couldn't swallow for sheer fear."
The situation was the "most stressful" he had encountered in all his years as a firefighter.
Mr Spittal was treated by ambulance staff at the crash site and was back at work yesterday afternoon, but he admitted he was "still a bit shaky".
Constable Rhys Martin, of Oamaru, said inquiries were continuing into the crash and a cause had not been established yesterday.
He could not name the victims late yesterday.
