The 19-year-old was with a 22-year-old man in Erdington, Birmingham, on Friday night when he was put in the car amid an outbreak of disorder, police said.
Soon after, police were called to nearby Hunton Road, where a dead man was found. They believe he was the man forced into the car.
The 22-year-old was not seriously injured. Officers were initially called to reports of disorder in The Gardens at about 20:50 BST. They were then called to Hunton Road about five minutes later, a West Midlands Police spokesman said.
Det Insp Warren Hines, from West Midlands Police, said: “I believe there were two vehicles involved in this incident a blue Mercedes and a silver VW Passat, and I would ask that anyone who saw these cars in the area around The Gardens and Hunton Road to contact me as a matter of urgency.”