The 40-year-old man was sitting in his car on Artillery Crescent, about 10am on Saturday, when he was attacked.
Police said the victim had accidentally bumped his car horn when a man in the passenger seat of a four-wheel drive behind him got out and attacked him.
Officers said the 28-year-old attacker punched the victim in the face repeatedly and kicked his car before driving away.
The attacker, who police said was a member of the Bandidos bikie gang, then returned to the scene and continued to bash the victim while he waited for police and paramedics.
When police arrived they found the alleged attacker nearby and charged him with common assault, assault occasioning actual bodily harm, affray, and breach of bail.
He will appear at Blacktown Local Court this week.