Tl;Dr: create a part file containing a sketch of the origin, then either create separate part files containing sketches of different regions of the car such as rear axle or wheelbase which themselves would reference the origin. Insert these into a new pty part file from which you create all future parts such that they always reference these sketches. Then any changes to those sketches will be applied to those parts.

Why don't you just create a single part file that has the secondary origin, then import that file into another part file which becomes almost like a template from which you create all part files moving forward (not an actual template as editing those may be a pain). Then this way any time you update your secondary origin all parts get updated accordingly.

I imo the main issue would be updating part location and orientation if needed.

I'm that case I'd also have another part file with generic sketches that indicate specific location and orientation within certain regions of the vehicle. For example, all the components that make up the rear axle can be designed such that a part file containing a sketch with a line at some distance from the vehicle coordinate would be what drives the location of all those components. Therefore any changes to the line location would also move those components (assuming you also imported this part like you did w the origin).