David Hallyday (born David Michael Benjamin Smet; 14 August 1966) is a French singer, songwriter and amateur sports car racer. Hallyday was born in Boulogne-Billancourt and is the son of the French singers Johnny Hallyday and Sylvie Vartan. David Hallyday is a first cousin of actor Michael Vartan. He is the older half-brother of actress Laura Smet. Hallyday is most known for writing music for others, including a collaboration with his father on the 1999 album Sang pour sang. He appeared in the teenage comedy He's My Girl (1987), also perfor…