Hato Hone St John transported the man to hospital.
His condition at the time was described as “moderate”.
“He was working on the car in the backyard of the property and fortunately there was someone home at the time,” the firefighter said.
“They heard him cry out, went to investigate, called 111 and that made a significant difference.”
The firefighter estimates he was trapped for about 15 minutes.
A St John spokesman said the man was “incredibly lucky” not to have been more seriously injured.
The hospital reported the 40-year-old was treated in the Emergency Department for minor chest injuries and was later discharged.
Firefighters were called to MacDonald Road at Matawhero on Thursday at around 8.40pm when a rubbish fire got out of control.
It happened near the rail bike base.
“The fire didn’t threaten anything but it took a while to put out,” a senior firefighter said.
An appliance and a water tanker from the city fire station responded.