In mission A-4, after hitting the dump truck 2 times, cut through the turn and make a right around the right curve. Jump by pumping the gas at approximately 30 mph. Go up the platform and fall through the hole, the police truck must be in the ditch, go on the side, turn, and hit it with the side of your car. After hitting the truck, quickly speed off and look on your left side,you will see a ramp, go over it, turn right onto the platform and activate the elevator.