The police are appealing for information to trace a man they wish to speak with following a crash in Hillingdon in the early hours of Saturday.
21-year-old Umier Iqbal from Hayes is believed to be in the west London area.
Police were called just after 3am to Shepiston Lane in Harlington following reports of a Mercedes having been in a collision with a tree.
Officers and London Ambulance Service attended. Three passengers were taken to hospital.
The front seat passenger remains in a critical condition. The driver is believed to have fled the scene.