A fender bender turned tragic Thursday when a man stepped out of a damaged car on the FDR Drive and was critically ­injured by a third vehicle that slammed into him.

A Cadillac and a sedan had a minor collision on the drive at 41st Street at about 7:30 p.m., sources said.

One the drivers got out of his car and was struck by a Mercedes-Benz. He was taken to Bellevue Hospital, where he was in critical condition.