The man realised his mistake and drove eight-year-old Scott McKechnie Skifjell to a remote house, when he woke him, telling him to go and knock on the door.
"I had fallen asleep in the car, and then I woke up to find a man telling me to get out of the car and into a nearby house to find my mother," eight-year-old Scott McKechnie Skifjell told NRK on Sunday.
His mother Kathleen Skifjell, who had just popped into the petrol station to buy a bottle of water, was thrown into a panic when she realised her car and son had gone.
"I thought I must have parked somewhere else," she told NRK. "I just couldn't believe that the car was gone."
"I was scared, but at the same time I managed to tell myself I had to keep a cool head. I thought I had to assume that whoever had stolen the car hasn't seen that there was someone in the back."
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She studied video footage of the man who had stolen the car, and alerted the police, who arrested a 31-year-old in connection with the theft on Monday.
Soon after, she got a call from the people living at the house where her son had been dropped off.