In the beginning of the Dark knight. Batman falls through the several floors of a parking garage in order to stop the scarecrow. His cape seemed to offer some sort of air resistance but he landed quite hard smashing the car. Once again Batman jumped out of a building to save Rachael from a fall. This fall was significantly higher and his cape had enough air resistance to save them and smash another car upon impact. The acceleration due to gravity is 9.81 m/s^2 so the cape must have decreased their velocity to a magnitude of survivability or Batman is just awesome.