Passive mode is only active while you are on foot (although you can still get ran over by other players, on the plus side, you can still run them over also). While inside a vehicle, you are able to shoot and get shot at and in the process, get killed. Your vehicle is not immune to Passive Mode. This feature, which can be activated through the interaction menu, is free ($0) to activate. Prior to Title Update 1.07 passive mode costed $100, but it was changed to $0 "so players could have more options with friends". As of Title Update 1.10, any player who kills a passive player must now pay their hospital bills, and vice versa.