A 30-year-old man has been arrested on suspicion of causing death by dangerous driving in connection with the crash which killed Rehan Shafiq.
The man was arrested on Wednesday August 22, and bailed until Wednesday September 26.
Three other men from Milton Keynes, two aged 22 and one aged 24, were also arrested in connection with the collision, are due to answer bail on the same date.
Nineteen-year-old Rehan Shafiq from Milton Keynes died after the Seat Ibiza he was travelling in hit a lamppost in Buckingham Road at about 11.20pm on Monday August 13.
Sgt Jack Hawkins, of the Roads Policing Department, is continuing to appeal for witnesses to the collision.
He said: “We are particularly keen to hear from anyone with information about a small dark car, which we believe was travelling out of Bletchley towards Buckingham before the fatal collision, but turned around at the scene and drove away back towards Bletchley without its lights on.”