A body structure of a passenger car, and especially of a convertible, features at least one side door on each longitudinal side of the vehicle. The side door, when closed, connects to adjoining fixed pillars via hinges at one end and via a lock assembly at the other end. For improved crash resistance of the body structure of a passenger car, and especially of a convertible, with a rear engine in the event of a head-on collision, a buttress assembly is installed between the rearward rim of the side door and the adjoining lock-side pillar. The buttress assembly effectively holds the side door in its closed position in the event of a head-on collision, while at approximately the level of the buttress assembly, the side door is braced by a hollow strut that extends in the longitudinal direction of the vehicle.
