I tried to get one of cars either Romero's Hearse or Black Voodoo by failing mission in mission "Four Iron". But if I snipe Haitian leader without anybody seen, mission fails and all of cars nearby dissapears. Also when I try to close behind him, there are haitian gourds everyware and they spot me which ever direction I try to come close to haitian leader. So I found a trick to get both of these rare cars at once with passing mission.
First I should tell that all of that Haitian gangs are not powerful men and their firing is absolutely inaccurate. All you need is to steal black voodoo and drive it to a garage. This is fairly easy. At the same time, Haitian leader will escape with a ROmero's Hearse. I thought I might wasted because I was surrounded by lots of haitians with shooting. But when I steal Black Voodoo, I lost only 3 armor. When you steal black voodoo and go to a garage, 4 haitians with a Romero's Hearse will chase you. But they can't get close to you if you drive properly. Once you stored black voodoo and see for that Roemero's Hearse that chased after you. It should be driving around you and waiting for your come back. Now take the sub machine gun and slowly fire until occupants drop down from it. Make sure you don't blow up the Romero's Hearse. Once 4 Haitians drop down, kill all 4 of them. It's also very easy because they are not accurate shooters and you will loose no armor. After killing them, steal that Romero's Hearse to a garage and go for kill Haitian Learder who are in another Romero's Hearse. You can either blow up his car with a minigun or just drive by. In this method, you can get both ROmero's Hearse and Black Voodoo with passing the mission.