The 35-year-old was found with multiple bullet wounds after the shooting at a junction in Yeading Lane, Northolt at 1am on Tuesday.
Pictures of the scene show a silver Mercedes with bullet holes in the driver’s window being examined by forensic teams.
It is not known if the victim was inside the car during the shooting.
A Scotland Yard spokesman said: “He was taken to hospital for treatment where his condition was not life-threatening.
“A crime scene was established while enquiries were undertaken. This has since been removed.
“There have been no arrests; enquiries into the circumstances are ongoing.”
Anyone with information that could assist police is asked to call 101 or tweet @MetCC quoting reference CAD 348/05Jul.
To remain 100% anonymous call the independent charity Crimestoppers on 0800 555 111.
