You sent me down a little rabbit hole, depending on how one defines sedan, the lightest I could find is the Peel P50 at roughly 60 kg. A better fit weight wise could be the Isetta at roughly 350 kg.

But neither option, including the robin feels like a proper sedan to me, and only the robin really checks the basic requirements.

Afaik the term “sedan” doesn’t really define the amount of wheels, but I don’t tend to think of a three wheeled vehicle.

So the first four wheeled sedan style car that came to mind was the Trabant, but that’s still 600kg.

Idk what the point of this text is…

Have a nice day, I guess?

What about ChameleOS?