Authorities say they received a tip that the vehicle of interest -- a 2011 Mercedes Benz E350 -- was under a tarp near 58th and Girard streets.
The car reportedly had extensive damage when it was found.
Police say the deadly crash happened around 9:30 p.m. Thursday at the intersection of 66th Street and Haverford Avenue in West Philadelphia.
The victim and her mother were reportedly walking home from the grocery store when a speeding vehicle came through the intersection and fatally struck the teen.
Video obtained by Action News shows the force of the collision was so powerful that the girl was launched several feet down the street.
Authorities later identified the victim as Dawn Watson, a student at Lewis C. Cassidy School. She was a first-year student who was already beloved by many, according to the school's principal.
Investigators are still searching for the driver involved in this incident.
Anyone with information is asked to call or text the police at 215-686-TIPS (8477).