The victim was pronounced dead at the scene from a gunshot wound to the head, Passaic County Prosecutor Camelia M. Valdes and Clifton Police Chief Mark Centurione said in a joint statement.
Police were called to the BP station on the westbound side of the highway after the man's body was found in his Nissan Maxima shortly before 11 a.m., they said.
"The initial investigation indicates that the wound was self-inflicted," the release says. "However, the official manner of death will not be determined until an autopsy is [conducted] sometime later this week."
Law enforcement sources told Daily Voice that the gun was recovered from the car, which had its driver's side covered by a white sheet.
"There was a lot of blood," one said.
Prosecutor's detectives were joined at the scene by members of the Passaic County Sheriff's Office, Clifton police, EMS workers and a medical examiner.
Click here to follow Daily Voice Cliffside Park-Edgewater and receive free news updates.