The story began when Auckland resident Kim McMillan and husband Cam left Hebe Cres in Papamoa to drive home to Forrest Hill last month.
The pair stopped at Subway in Ngatea at 3pm for about 10 minutes and got home two hours later.
Then they heard the meowing.
"We got home, started to unpack the car and five minutes later we heard this meow," Mrs McMillan told the Bay of Plenty Times.
Mrs McMillan said the vet believed the kitten was not a stray.
"It is somebody's pet. It was very, very playful and liked attention. They did say it was lucky to be alive. It was pretty hot in there. An engine for four hours, can you imagine how hot it would have been?
"We called it Lucky, as it was lucky it survived that trip."
Posts on Facebook have been shared hundreds of times to find the kitten's owner but no one came forward.