I believe "design" and "origin" are pretty "philosophical" - they are more of a statement than actually providing information about a particular car.

The place of assembly, OTOH, can be informative as to indentifying particular characteristics of the car. Do remember this field can be optional - i.e. you don't have to have flags for EVERY car. If the place of assembly is certain, we just add it to provide more information, just like we sometimes add production year or trim level.