I don't know if it was my imagination or not, but it seems like at the beginning of the game you could drive by gangs and everything would be cool, but later on in the game it seems like the gangs that you performed the most missions against would shoot at you whenever you were driving by them. Anyone else noticed this?
I think it's because in the beginning you didn't harm them yet, but when you get to the missions that you are supposed to kill them, then I think that is the start when they will be hostile towards you.