I don't think they're special - if additional sites relating to the same manufacturer are identified (through submissions or otherwise) - an individual category will be created and the listed sites moved across I presume.
I am working on a Gaz category myself currently - and will move that site across to it once it's live.
NB: This might be a language confusion - speciality has several meanings - and in the context of car marques should be taken to mean less well known ones that there may only be one or two sites for.
Per
http://www.oed.com/
Speciality
5c: A thing or article specially characteristic of, produced or manufactured by, a particular place, business firm, etc.