A boy of four drove his mother's car on a late-night trip to a video shop in the US state of Michigan, police say.
The unnamed boy had been driving without headlights
Although too small to reach the accelerator, he put the car in gear and the idling engine took him to the shut shop, 400m (437yds) away in Sand Lake.
On its return journey the car's weaving attracted a policeman - who followed the apparently driverless vehicle.
The youngster hit two parked cars and reversed into the police car before he was stopped. He will not face charges.
The policeman who discovered exactly who was behind the wheel, Sgt Jay Osga, said: "He knew how to go from forward to reverse."
The boy's mother - who will not face charges either - said she taught him how to drive while he was sitting on her lap.
"He's four years old. His mom didn't even know he was up," Sand Lake police chief Doug Heugel told the Grand Rapids Press newspaper.
"I don't think he even realises what he did."