A door assembly for a motorized vehicle includes a door configured to move between an open position and a closed position, a first member defining a first axis, and a first support member pivotally coupled to the door and defining a second axis. A linkage assembly includes a first arm and a second arm. The first arm and the second arm are pivotally coupled to one another, where the first arm is coupled to the first member at a location offset from the first axis and the second arm defines a first slot. A cross member has a first end and a second end. The first end has a first pin for slidably engaging the first slot and the second end being coupled to the first member. The door is movable between the open and closed positions as the first member pivots about the first axis.