Mr Kreling, a financier from Shelly Beach, hit the bird when it ran in front of his car near Helensville.
"I hit it straight on and I heard and felt the impact," he said. "I thought I had taken it out."
The next day as he was taking his rubbish bin out he heard the clucking from the car bonnet and saw the feathers. "I saw the little eyes looking at me and realised the chook was alive," he said. "It must have gone straight through the radiator grill when I hit it and the mesh closed behind it.
"It was like it was in a wee cage and it probably survived the night because of the heat from the radiator. I chucked some bread in and it ate it."
Mr Kreling freed the bird by cutting through the grill with garden shears and took it to a vet where it was found to have a dislocated leg but was otherwise in good health.
Impressed with the hen's resilience, Mr Kreling named her Blessy because she was blessed to have survived. He has now built her a hutch in his back garden.
He was delighted when Blessy yesterday laid her first egg since the accident on Friday.
"She is a bit of a miracle hen and I feel duty bound to keep her," he said. "She is quite a character."
Since the Herald on Sunday published his story, Mr Kreling said he had received quite a few comments on Facebook with the link being shared by friends around the world.
"So it's gone to a couple of people in America and a couple of people in England," he said.
He had yet to hear from any potential owners, but said if they did come forward he joked they could "pay me $511 for the damage to the grill", and the vet's bills, he said.
"It's up to them", he added laughing.
But if no-one comes forward, he will keep Blessy.
"She's almost part of the family. The cat looks at her and goes, 'meh'. But ... the cat's not bothered at all, it's quite funny."
However, the hen was "still hobbling" ... like an old lady on a zimmer-frame, [but] she goes alright."
- additional reporting: Patrice Dougan