Chloe Rodriguez had been missing since Nov. 9, Radio France Internationale reported.
Police discovered her in the trunk of a car near Offenburg, close to the French border, during a routine traffic stop.
The 32-year-old driver, who was arrested at the scene, was from the same region as the girl. He had a number of prior convictions, including one for sexual assault.
Rodriguez's parents went to Strasbourg to be reunited with their daughter Friday night.