It became even more of a mystery for it owners Jamie, 11, Benny, 9 and Emma, 7, when his guinea pig girlfriend Poseidon also disappeared from the well-equipped hutch on the back lawn eight days later.
It wasn't until the children's nana Carol Trewheelar went to check on the family's home while they were away that they found out Patches was alive and the story began to unfold.
Trewheelar went over to their home in the hope of finding and feeding Poseidon that she discovered a note from the SPCA.
Baffled Trewheelar contacted the SPCA and was told they had the Snow's guinea pig.
He had been flung from the Snow's Ford Focus at the roundabout at Countdown near Auckland Airport when they were picking up Trewheelar, she was told.
A taxi driver saw the furry rodent running on the road and stopped to save it. Other motorists also slammed on their brakes while they chased Patches across four lanes of traffic.
He was finally nabbed and taken to the SPCA, who carried out a full vet check. Video footage obtained from Auckland Airport showed the guinea pig falling from the car and tracked the licence plate to his Mt Eden home.
"They said that on the video he had fallen out from the back of the car. I just said, 'I can't understand how that could happen. It's just bizarre that you could pick up a guinea pig on CCTV footage'. But she (SPCA inspector) assured me that's what happened - they saw him come out of the car, they saw the number plate of the car and so that's how they tracked it to Mt Eden," Trewheelar said.
Patches must have been stowed away under the car and was flung out when going around a sharp corner, she said.
"She went careering round there (the roundabout) and poor old Patches obviously fell out. The guy who picked him up was a taxi driver. And the lady at the airport said it wasn't just him who had to catch this jolly guinea pig. He had about 10 people, they stopped the traffic and these people - Patches went backwards and forwards across those four lanes a couple of time - with these people after him."
Trewheelar was even more baffled when she went to collect the guinea pig and discovered it was Patches rather than Poseidon who had been found.
"It was a long time for him to be away and he'd obviously been living in their Dad's car for 10 days and maybe when Sean came home he hopped out for a bit of something to eat and hopped back under the car again. And he'd gone off to work with Sean that day and of course we would still be looking but he's be on board the car at Newmarket in the car park."
She took him home and, after retelling the story to the children's father, Sean, he crawled under his car to see where Patches had been hiding.
As he was looking, Poseidon nonchalantly walked out of the warm spot and back across the lawn to the hutch.
The furball joined Patches and the two of them started chatting away.
"It was just unbelievable.
"They are thick as thieves these two."
The family is still amazed about the adventures their two guinea pig went on.
"It still strikes me as unbelievable that someone went to that much trouble to catch a guinea pig and we ended up getting our guinea pig back. And we would love to say thank you to that taxi driver, but nobody knew who he is."
An SPCA spokeswoman confirmed the guinea pig had a vet check-up and was returned to his owner two days later after sighting video footage of the incident.
