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."
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.