Police in Soest, a town in western Germany, said the boy’s mother had called them early on Wednesday after she noticed both her son and car were missing.
The child was eventually found on a motorway where he had pulled up in the automatic VW Golf and put the hazard lights on.
He told officers he started feeling “uncomfortable” once he hit 87mph.
“I just wanted to drive a little bit,” he said.
The police force posted details of the incident on its Facebook page.
“Fortunately, no one was hurt and no property was damaged,” it said.
The mother said her son regularly drives go-carts and bumper cars and has in the past practised driving a real car on private property.
The legal age for driving in Germany is 18.