Different nodes publish their own car_cmd. Inside the car_interface only one gets mapped to /.../car_cmd_switch_node/cmd The mapping is done by the car_cmd_switch_node, by reading the FSM Mode directly This is done according to the following configurtation file https://github.com/duckietown/dt-car-interface/blob/daffy/packages/dagu_car/config/car_cmd_switch_node/default.yaml