The crash happened on Saturday at around 8.35pm on Laleham Road near Shepperton Rec, involving a black moped and a silver Audi.
Police say both vehicles were seen driving dangerously before the collision, and a car bumper was found at the scene.
A 17-year-old was arrested for affray, and two others aged 17 and 19 for assisting an offender; all have been bailed.
Any witnesses should contact police on 101.
