Not really. As it is, they just need one type of casting for driving cars, which they then can blank off as necessary, which is a lot cheaper and easier than having 2 designs.
Casting!!! (and you are apparently a mech eng student
)
Bodyshells panels from any of the usual suspects (A, B, C, H, S or S) are made up from "planks" of twin wall Aluminium extrusion that are welded* together (no castings to be seen). The body sides are made up from 5 extruded horizontal longitudinal "planks":
a) a curved cross-section lower section (and join to floor),
b) 3 flat sections at mid level
c) and a different curved cross section including roof join at high level.
The c) "plank" is usually the length of the whole car, the a) planks can just run between the doors (they are over length at this stage and trimmed later) or along the whole car length depending on manufacturer / floor design.
The 3 flat b) planks the upper and lower just run between the doors (they are over length at this stage and trimmed later). The middle b) plank just runs between the window and doors .They are over length at this stage and trimmed later) -lots of short offcuts can be used for this!
This allows quite bit of material saving / efficiency.
The body side is then put in a jig and a CNC milling machine trims the ends and does the precision cutting for all the door, window, door button unit and bodyside indicator light (orange light) apertures where the door and window frames etc. are later added.
See this photo from Paul Bigland's collection of a 700 body side post milling:
http://paulbigland.zenfolio.com/p487954781/h73b913ba#h73b913ba
Note the milling machine in the background and the notches in the PTFE jig profiles where the joins between the planks are as the exterior welds have yet to be ground. the body side in the photo is from the right hand side of driving car so the gap for the drivers doors and slightly shorter body-side length allows the jig to be seen.
*The actual join is mixture of shape impingement followed by welding after they have been "clicked" together this photo shows the actual joins better post weld grinding:
http://paulbigland.zenfolio.com/p487954781/h783dad00#h783dad00.
The real reason is of course that the buffet can be removed and replaced with seats in later life far more easily!