In Istanbul's The Chase mission, there is no easy way to describe how to drive after Calita other than saying that there is no reason to run into her when she is in the car, because her mass is much greater. After you chase her to the bridge, the intermission sequence shows her jumping the drawbridge. Go over to the bridge control room on the left. Go up to the yellow box and press L. The bridge will be lowered. Get back in your car and chase her while she is on the run. She will run into a motorcycle place. After the intermission sequence of her hopping on a bike, chase her on the bike. Applying the brake to turn with the bike is needed very rarely. Try releasing the gas rather than braking most of the time. Try to catch up to her, then bump her with your bike to complete the mission.