The story of Johan model cars involves their rise to popularity in the model car industry due to their unique and accurate reproductions. They became a favorite among collectors for their attention to detail and authenticity.
I don't know for sure. The ending of such a manga can be quite unpredictable and might not have been revealed yet. You could try discussing it with other fans to get their speculations.
I'm not really sure if they end up together. Different people might have different interpretations. Maybe you can dig deeper into the manga and form your own conclusion.