He was the 77th person to die on Irish roads this year.
The collision happened on the N1 near Thistle Cross on the main Dundalk-Newry road at around 4am.
The driver of the car was killed, while the driver of the truck was uninjured. There were no other injuries.
Gardaí have asked witnesses to contact Dundalk Garda Station at (042) 9388400. The name of the dead man has not yet been released.
Meanwhile, the name of the man killed in Sunday evening’s road traffic collision at Longwood, Co Meath, has been released as Christopher Slevin, aged 24, from Donore, Longwood, Co Meath.
Of the 77 people who have died in road accidents this year, 17 were pedestrians. Thirty-nine drivers were killed and one cyclist.