The teenager, who lived in the area with his mother, was knocked off the moped by a black Mercedes B Class at around 6.30pm on Tuesday in Bickley Road, Leyton, and then stabbed several times by three attackers as he lay unconscious in the road.
The car was found on Wednesday in nearby Carlisle Road area of Leyton, a few hundred metres away, and remains there for forensic examination.
Detective Chief Inspector Chris Soole from the Homicide and Major Crime Command, who is leading the investigation, said: “We are treating the recovery of the car as a significant development in our enquiries, which are still very much in their early stages.
“Jayden’s family are being fully supported and kept updated by our team. This is a truly heartbreaking time for them and we are doing everything we can to find out who was responsible for Jayden’s death.”
Mr Tucker said it was too early to ascertain a motive or say whether an incident a few streets away from the crime scene on Wednesday when a man was slashed across the face was linked.
He said: “The overriding factor is he’s 14 years old. A lot of people are saying ‘young man’ – he’s not. He’s a boy. He’s 14.