the following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure . furthermore , there is no intention to be bound by any theory presented in the preceding background or the following detailed description . the passenger car underbody structures shown in the fig1 and 2 are of identical design except for the different tail overhangs and the different wheelbases , so that for both figures same reference numbers are used . according to fig1 , a detail of a passenger car underbody structure 10 is shown , which comprises a front vehicle that is not shown , that is connected to a middle underbody structure 11 . the latter comprises lateral longitudinal frames 12 ( only one is shown ), on which a middle floor panel 13 extending between these is fixed , for example , through welding . the middle underbody structure 11 is connected to a rear underbody structure 20 , which according to this exemplary embodiment is equipped with a long tail overhang 21 with respect to a rear axle that is not shown . the rear underbody structure 20 in the present case is designed for a long wheelbase and , like the middle underbody structure 11 , comprises lateral longitudinal frames 22 , the rear ends of which are connected to a cross member 23 . between the lateral longitudinal frames 22 a rear floor portion 24 serving as trunk floor is arranged , which is connected to the cross member 23 , the side members 22 and a cross member 24 . 1 , for example , by means of a welded connection . a rear floor panel 25 likewise arranged between the side members 22 , whose end facing the middle underbody structure 11 is connected to a connecting profile 26 by welding , which in the present case is embodied as deep - drawn sheet metal part and serves as a so - called heel plate is connected to the cross member 24 . 1 . said heel plate is equipped with a step - like shoulder 27 , which on its region facing the rear floor panel 25 is provided with a horizontal web 28 , which is connected to the rear floor panel 25 generally through welding . arranged in front of the horizontal web 28 in driving direction ( indicated by an arrow ) is a vertical portion 29 connected to said web , to which in turn a horizontal portion 30 is unitarily connected . the horizontal portion 30 in the present case is molded as a shell that is open on one side and created through deep - drawing of a sheet metal blank with shell side walls 31 and a shell rear wall which is formed by the vertical portion 29 . the shell side walls 31 in the present case have an angled - off region designed in the manner of a flange at their free edge , which serves as connecting flange 32 . in the horizontal portion 30 , in the region of the vertical portion 29 , adjacent to the shell side walls 31 , mountings 33 are molded in ( see also fig3 in this regard ), in which the side members 22 of the rear underbody structure 20 engage and are fastened . the horizontal portion 30 on its end 34 facing the middle underbody structure 11 is of an open edge design and connected to the middle floor panel 13 subject to forming an overlap region 35 generally through welding . with a rear underbody structure that is suitable for a long wheelbase , as the rear underbody structure 20 represents , the overlap region 35 is spaced from the vertical portion 29 by a predetermined dimension x 1 . the overlap region 35 formed through the overlapping ends of the middle floor panel 13 and of the horizontal portion 30 forms a connecting portion 36 for coupling the middle underbody structure 11 to the rear underbody structure 20 . a further connecting region 37 between the middle underbody structure 11 and the rear underbody structure 20 is formed between lateral side members 12 and the lateral side members 22 . with a rear underbody structure designed for a long wheelbase and a large tail overhang , as is represented by the rear underbody structure 20 according to fig1 , the lateral side members 22 have a length l 1 . with an underbody structure 40 designed for a short wheelbase and a shortened tail overhang , as is shown according to fig2 , the length l 1 of the side members 22 is shortened by a length portion δl to a length l 2 . the length portion δl can be composed of part length portions of which a part length portion is cut off to length on the free rear end of the lateral side members 22 , as a result of which a tail overhang 21 . 1 is created , the length of which is shortened relative to the tail overhang 21 shown in fig1 . another part length portion can be cut to length on the side members 22 , on their ends facing the middle underbody structure , as a result of which a passenger car underbody structure is created , the wheelbase of which relative to the wheelbase of the underbody structure as shown and described in fig1 , is shortened . the passenger car underbody structure 10 shown in fig2 has a shortened wheelbase compared with the passenger car underbody structure 10 , as shown in fig1 . the overlap region 35 between the horizontal portion 30 of the connecting profile 26 and the middle floor panel 13 however has a width b , which corresponds to the width b of the overlap region 35 of the underbody structure 10 according to fig1 . in contrast with the overlap region 35 for the long wheelbase according to fig1 , the overlap region for the short wheelbase according to fig2 however is spaced from the vertical portion 29 by a predetermined spacing x 2 , which is designed shorter than the spacing x 1 . the shortening of the spacing x 2 leads to a shortening of the connecting profile 26 by the dimension δx ( see fig3 and fig4 in this regard ) for creating a uniformly wide overlap region . as is evident both from fig1 as well as from fig2 , the side members 22 on their top side in the region of the rear floor panel 25 comprise mountings 22 . 1 shaped in an elongated manner which serve for the rearward fastening of rear seats that are not shown . for the fastening of the rear seats on the front side , fastening elements 28 . 1 are provided on the connecting profile 26 in the region of its vertical portion 29 , which in the present case are designed frame - like and are fastened to the horizontal web 28 , for example , through welding . fig4 shows a second exemplary embodiment of a connecting profile 40 , which merely differs from the connecting profile 26 in that it is divided into two profile portions 41 and 42 in width direction and comprises a recess 43 that is open on the edge , which in the present case serves to accommodate a function part 44 , such as , for example , a cover for a handbrake cable or the like . while at least one exemplary embodiment has been presented in the foregoing detailed description , it should be appreciated that a vast number of variations exist . it should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples , and are not intended to limit the scope , applicability , or configuration of the present disclosure in any way . rather , the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment , it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims and their legal equivalents .