A car chase through Brooklyn ended in a horrifying scene yesterday when the driver of a black Infiniti crashed into the back of a flatbed truck and lost his head. According to a witness, the 22-year-old driver was going about 80 miles per hour when he slammed into the back of the stopped truck at the end of the Atlantic Avenue exit on the Gowanus Expressway. “I’m in shock seeing something like that — when they pulled the car out, the body was leaned back in the seat but the head wasn’t there,” a witness told the Daily News. After the crash, a woman jumped out of the passenger seat and tried to run away. She quickly gave up and was taken away in an ambulance.