The cops. The fucking cops. It takes a while to lose them, and the game tells you at the beginning that after you exit the flashing red/blue spot you can hide in places. Except this doesn't work all the damn time, since either cops will spawn just near you, or know your hiding spot even no matter how secluded it is and a cop will go by your place. And no, there's not even a "last seen going on" chatter. They just seem to magically know where you are. To a lesser extent, but still annoying, they'll ram you aggressively in the rear too. And these fuckers start to pack heat at 2 stars which can happen easily, and oh, some of them will be carrying shotguns which are very lethal in this game. They are accurate with guns, even when you're going fast inside a vehicle. And they tend to shoot the tires off your car.