The incident occurred around 3:30 a.m. near 11th and Lehigh Avenue.
According to police, the suspect approached a driver in a Mercedes and punched him in the face.
He then took the victim's car and drove to 11th and Cambria where he lost control and crashed into a parked car.
The suspect then fled the scene on foot.
The unidentified driver is being treated for head injuries.
So far, no arrests have been made.