In the city, go on the highway that looks like you are in the desert. On the right side of the highway is a spot with a ledge. Find the ramp that leads onto the ledge and stay up there while using your car as a shield so the police can't shoot you. It will take a while before the police can get you. All the officers will get out of their cars and walk towards the ramp. When this happens, jump off the ledge and drive away in a police car.