I hope you are not serious.
In case you are: no offense but you don't seem to have any idea how a complex 3D game engine works. The car object's XYZ position and orientation (rotation) is most likely stored in the save file directly. It's surely more than a simple boolean flag.
Yours is upside down (wrong rotation). For many others, like me, the car most likely fell through the ground at some point in time as
CapacAmaru illustrated above - permanently giving it wrong position coordinates when the game is saved and subsequently loaded.
To fix that for existing save games, the game would need to check any critical quest-related objects at load time and correct invalid positions of such objects automatically if applicable. And then it depends what they make the game detect as "invalid" - only position (too far away) or also rotation (upside down)?
However, that's just speculation on my part. They could also have gone an entirely different route - I don't know how their engine works and what possibilities they have. It's also possible they could fix the bug to prevent it from happening with 1.05 for new players but can't fix existing save games that already have a misplaced car (which I hope is not the case). But we don't know. When the patch lands in PC land and more affected people can test it, we'll know more.