Try to get in taxi driver shoes. Your task is to look for passengers and transport them to place where they ask You to drive. All destinations and the possible locations of the passengers are flagged on map.
While you are looking for passengers, time is stopped and you can ride slowly through the maze of the city. But once you take a passenger, countdown starts and you must be able to take passenger to the destination in time.
If you make it faster, more money you will earn. Do not forget to check gasoline sensor and periodically drive to nearest gas station. And of course try to drive more accurate and do not crash into others.