[PROBLEMS] To more increase the capability of a vehicle despite the fact that mankind cannot catch up an increase in performance of the vehicle by forming the vehicle to give less damage to persons in the event of the accident of the vehicle and to minimize emission from the vehicle. [MEANS FOR SOLVING PROBLEMS] The safety of occupants in the vehicle depends upon the degree of collapse of the vehicle at the time of collision. The non-pollution of the vehicle depends upon the speed of the design change of the vehicle to alter the specifications based on the latest technologies. For this purpose, a carriage allowing the easy design change must be developed. A structure allowing the easy change of the carriage portion of the vehicle has been developed.
