Detectives said the teen was first attacked in a secluded part of Witton railway station, near the Aston Villa football ground, about 120 miles northwest of London, sometime between 7 p.
A major investigation, involving detectives from the British Transport Police and West Midlands Police, is under way to try to identify both attackers and appeal for witnesses.
He was wearing a tracksuit top and bottoms, black trainers and was in his early 20s.
The victim had walked to the station with her friend but was led away by a man who approached her.
The second attacker is also described as Asian, in his early 20s, 5 feet 6 or 5 feet 7 inches tall, with a large build and a close-cropped beard and was wearing a blue shirt and black jeans.
The first attacker is described as Asian with light skin, brown eyes, a skinny build and about 6 feet tall.
But after getting in the car, she was raped a second time by another man.