Them Sindacco Assholes!
Vinnie is all "blocked up" in his cubicle, before he tells you that the dealer you dropped off really was running scared of the Sindaccos - because some of them whacked him. It was time you put some Sindacco dealers out of business.
Revenge Is A Dish Served Cold
Your first dealer is really no match - you can perform a successful melee attack quite easily. Just remember that he drops cash and that you watch your health. The other two are easily roadkill in a few seconds.
Reward: $250, Car Salesman side mission unlocked
The Car Salesman side mission is at Capital Autos, Harwood.