The mother initially thought the youngster had thrown something at the windscreen, Constable Henneker said.
"She went out to see what was happening and saw the car was full of smoke. She grabbed a fire extinguisher, opened the car doors and put out the fire that had started in the front passenger footwell.
"The fire was just getting going. It had burned and melted the car's dashboard and radio and it was the heat from it that cracked the windscreen," Constable Henneker said.
"She grabbed the child and got him out of the car. He was conscious but had suffered serious smoke inhalation and some slight burns."
The mother called 111 for help.
"She arrived at that car in the nick of time," Constable Henneker said.
"They were very very lucky. Another 30 seconds and the boy would have been far more seriously injured, or worse."
The ECT rescue helicopter flew St John paramedics to the scene.
"The boy was treated initially by the St John team from Mahia and they called in the chopper," said St John Territory manager Shane Clapperton.
"He was flown to Gisborne Hospital in a moderate to serious condition."
The youngster was admitted to hospital and the latest is he is in a satisfactory condition.
- Gisborne Herald