To me generic codes are better than too-specific ones, as I already said for other vehicles.
same for Mercedes, people will search for W121 if they want that model, and then may miss all these specific ones. If one wants just a body style, there is a filter for that. And I'm not sure that having a way to filter on engine type is useful.
A solution would be two codes : a "generation" code for the generic code and then use the chassis field for the specific ones. But I don't know if it is good to add even more info or if it makes more difficult to maintain.