Police say the victim, a man in his 50s, is well known to them, but they are not revealing his identity.
Police say they received a tip and discovered the body inside a vehicle Saturday morning.
They say the man suffered serious injuries to his upper body, but won't disclose whether a firearm was used.
Investigators were on the scene well into Saturday afternoon.
Police say they have no suspects.
There have been a number of killings in Montreal in the past couple of years involving family members or associates of reputed Mafia boss Vito Rizzuto, including his father and his son.
Rizzuto, 66, served eight years in an American prison on racketeering charges and was immediately deported back to Canada upon his release in October.
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